Well I actually just got around to trying out the demo for the game and am definitely gonna invest in it! Im a huge GalCiv2 fan, but I have always preferred Real-Time Strategy over Turn-based. So when I heard of a 4X RTS I was really excited!
I like a lot of the ideas expressed in this forum so far and thought I'd include my two cents to the matter, however please do realize i have only played the demo and so input on any mistakes I make would greatly be appreciated 
thanks
1) PIRATES: 
<("Avast ye filthy space lubbers") One of the things that always frustrated me about Galactic Civilizations is that Pirates appeared out of nowhere... and in a random medium map in Sins just now I went up against a huge pirate fleet that came out of where you ask? NOWHERE. But then again I haven't played the extended game and I didn't exactly get to exploring the entire galaxy yet. Maybe there is a Pirate Home world out there where all those frigtates were created?
- I also agree that watching the Pirate screen to see if I have a bounty on my head at the moment is disappointing. I think pirates shouldn't be going after fleets of other nations not for a "bounty" but rather personal gain... much in the same way current races already do. Attempting to expand there influence into systems surrounding themselves and building their fleets in the same way current players do as well! 
- I saw that planets have a Allegiance percentage based on how far away they are from your homeworld, perhaps if Allegiance isn't high and the military presence in the area is not very high either, then civilian ships may start leaving and population drops and they head to colonize their own planet, and thus becoming there own faction (or Pirates and perform as such)
2) SPACE TRAFFIC: Which leads me to my next point, and I read a few times in the forum and I like this idea very much. As I stated earlier I think that if a colony is unhappy, then colonists might go searching for a better life out there. But this would not be the limit to civilian traffic, perhaps you could have transports transporting slaves, or redirecting citizens or supplies. Or individual planets trading with other races close to them if a trade agreement is present. All of this, that is, what is done by the citizenry would be out of your control but you would see the benefit in the form of a cut of the credits 
In truth I think there needs to be more of an aspect on a Civilization other than just military expansion for resources... I will try to discuss more in depth later. 
3) FLEET STRENGTH AND HARDPOINTS: One thing I noticed fairly early on was how long it took for fleet battles to take place. I watched a frigate taking damage from my Capital Ship and was thinking that little thing wouldn't last a second under that kinda fire... I like how this was handled in Empire at War personally, although I didn't really like the ground combat and thus the game as a whole, but I thought that the space battles were very engaging. This was in part due to the use of hardpoints on the hulls of ships (such as its engine, shield generator and laser cannons) and I think Sins would benefit greatly from a similar set-up. That after shields are drained the ship won't be able to sustain much more fire before its neutralized. This would speed up play in a certain regard and keep fleet numbers down (I personally feel that they get a little large and it hurts performance at times)
- I also like how ships in Empire at War would fall apart as their damage increased, with parts of the hull breaking off and floating through space, and you would see the area around the ships ripple as it was being destroyed. 
I mean a stupid game like Empire at War did it! I definitely think that Sins could!
4) BOARDING PARTIES AND INVASIONS: I think it would add a new level of strategy if the game incorporated the use of soldiers in different ways. Such as ships being launched from a Cruiser (much like fighters and bombers do from capital ships) that could board an enemy ship whose shields had been terminated and then attempt to turn it over and use it against the enemy. Kinda like this:
- Of course this idea would be more useful if the ships could be customized, and thus one enemy ship might be a major target to attempt to overtake, but I understand that custom ships would be very hard in a game like this and wouldn't help with micro-managment, unless you could tell shipyard governors to focus on a certain type of ship based on current technology? and they just make new versions or models of current ships? Ooo! we may be onto something here? Probably not, but hey I tried. 
- Also planetary invasions would be a nice addition, and I would not be upset with a similar set up as Galctic Civilizations. Because I've found that planetary invasions can be very tedious endeavors. So just a simple set-up based on morale, technology, soldiering ability and chance would be nice. Of course in an RTS the effects would be more drawn out other than an entire planet being taken over in just one turn! 
- Of course, there would then be a new military tech tree featuring soldier progression such as new weapons and strategies that would automatically add to soldiering ability.
5) DIPLOMACY: One thing that has always really frustrated me about Real-Time Strategies was how diplomacy always took a hit in its design. I suppose I don't understand game design but I don't quite understand why a similar design to that of Civilization and Galactic Civilizations is not possible. Yes I could see how a race suddenly popping up while your trying to engage their fleet might be annoying, but what about requesting your audience?
- I think its silly that the other races give you "missions" or whatever they are called, and if you complete them then that is the only way to gain their trust and eventually make peace. It makes me feel inferior... like some sort of minor race 
even if I could kick their butts. I think it would be better as a threat "give us X amount of credits or else..." 
- I think everyone should start out in peace and war becomes a later option, based on your current strategy and location etc. etc.
- I also believe that the exchange of planets and/or ships, technology, and artifacts should be included in diplomacy as well. You could get hardcore, and say that you will send population from your planet to one of theirs for money, much like a slave trade but micro-managment might get too heavy.
- In truth I do not believe this would be any more demanding than the current set-up 
6) FROM CIVILIZATION TO EMPIRE: As I stated earlier, I believe that any game of this caliber should focus on more than just shoot, dominate, and destroy. I think every action you take should be a thought as to the repercussions it will have on your empire as a whole. "Do I go to war with this faction, knowing that my planet A does a lot of trading with their planet B and risk my population becoming unhappy and deserting me because their trading economy is being challenged?" "Do I attempt to take a planet that has an artifact I need, knowing that if I declare war, I might lose the trust and support of the people on a principle and influential planet whose many children are now running my fleets?"
- Yes I know you protect your planets, I know you protect your resources, but have you ever stopped to consider the people? Or how about the culture- developed by the very same people you have been disregarding- that you are exuding into the galaxy around you? I believe that this is the biggest thing that RTS's tend to disregard, and many games do overall. I know it might be hard to implement, but I think people need to have a voice, and shouldn't always support my calls for war, and if I push too much they just might pull away... <(WAR!!) 
In Conclusion, I thoroughly agree with more races, more individuality between those races, and if possible more customization in strategies such as one ship being good against another based on its design (Remember the governors ) However I love what I saw from this game, I just think its so close to being the absolutely perfect, why not go the whole way?!? 
Thanks for listening, I would love to hear from you guys concerning my post whether you agree or disagree with any of my points!
