First, I will tell you that I am generally fine with the economic system in GCII. It's definitely not perfect, and if they choose to revise it, I will be thrilled, but it doesn't kill the game for me.
I am also OK with the global budget allocation. My more micro management side sometimes wishes for more planet-level control, but - AI programming issues aside - I understand how this could make micro management extremely tedious in large games. I actually think that the planet-level specialization buttons are a great work around for this issue.
As far as the production sliders go, I definitely understand the complaints about their inefficiency/lack of expalinability with how things work in the "real world".
Ultimately, we just have to learn to live with some things that seem a bit frustrating - like the fact that we might make more than enough cash to fund our industry/research at higher levels, but can't get our factories/labs to run at anything higher than a 100-M,S, and/or R rate. I know everyone is trying to put logic in place to explain why this could be, but none of it will ultimately make sense.
If my budget is positive, but, for example, my research slider is at 50% - why can't I up my research production to, say, 60% utilization. The attempted "real world" answer to this is generally that, "Well, your infrastructure (people, power consumption, etc.) can't work/power any more research despite your having the financial means to pay for it."
OK - fine. But then, why can I instantaneously build another lab and have it immediately go into production at 50% capacity? Those workers wouldn't work in the "crowded" existing labs, but are now happy to work in a nice, shiny new lab? Also, by building this new lab, I have just increased my total spending on research (empire-wide). By building a new structure, I have effectively "fooled" the system into allowing me to increase my expenditures. (Example: My income is 105. My total research and industry output capability is 100, and my output slider is set to 100%. My sliders are at 25-25-50 (M-S-R), therefor, my industry output is 50 (M+S) and my labs output is 50. If I build a lab that has a base research value of 10, then I will be producing 50 industry (25M, 25S) - the same as before - and 55 research (50 from before, plus 50% of the new 10 I just built). Now I am spending all of my income (105) on my outpts (50+55). Why do I have to resort to trickery to accomplish this?
(Also, I get the fact that I can only do this for so long, because I will run out of buildable space. Still, it seems like I have to resort to a cheap trick if I really want to run my economy at its full potential.)
No matter how you try to explain it, it doesn't make a lot of "real world" sense.
Again, though. If the devs want to revise this I will be thrilled, but I am willing to live with it the way it is. It doesn't kill the game for me - it just doesn't make much logical sense to me at times.