1. Same engine, same problems
Actually, the lag in online multiplayer has improved dramatically with the most recent patch.
2. Poor numbers in do pre-orders show lack of interest.
It's difficult to take pre-order numbers seriously since only fools do full-priced pre-orders. Besides, the game is going to (presumably) be marketed to people who have never heard of or played Sins before.
3. No Steam support will hurt sales prospect
I suspect that people who are interested in the game and who have the ability to use Steam can figure out how to use Impulse.
4. More factions increase unbalance in already unbalanced game which may delay launch even further and put a pinch on funding
It's fairly well-balanced. There are pro players out there who specialize in each faction and who can kick your ass regardless of which faction you're playing.
6. Sins is too slow in multiplayer. If multiplayer continues to move at a glacial pace, less reason to buy a legitimate copy of the game
WTF are you talking about? Your average 5v5 only goes for about one hour, thirty minutes.