I assume (dangerous, I know) that the point of this would be a PBW game. You could only expand a certain minimal amount without help from other factions. Sure, the Spaceborne faction could build tons of ships--except they couldn't research bigger ones very quickly or pay for them. The Colonials could expand quickly, but they couldn't defend themselves very well.
The way I see it right now, colonial factions have the early game advantage (first pick of all planets), technologist factions would have the mid-game advantage (high-tech ships, although quite small), and spaceborne factions have the late game advantage (big ships can hammer dozens of small ones, although they would probably take some beatings from the technologists).
In the same light, the colonials seem to have the most desireable product until the various factions are established; whereas the technologists would the most valuable to everyone else afterward (research your own advantages faster). Facility-building factions (industrialist and technologist, mainly) also would get the bonus of additional production while building their high-tech facs on other people's planets.
You could also consider an engineering faction, with improved maintenance (those Crystalline facs) and repair. Maybe even reserve the quantum engines for them.
All in all, sounds like a great time, and carries a slight resemblance to SE4 Play by Committee. Speaking of which, let me insert my shameless promotion to come join us! Multitudes of governor positions are open, and our war seems it will soon open an additional front or two! See sig for link.
[ April 26, 2004, 22:27: Message edited by: Krsqk ]