I'm so glad to see that Sins II is coming along so fantastic. It looks amazing and the gameplay is great, I can't wait to see the Advent and Vasari!
I've been thinking of ways to make the factions really stand out from each other in new ways based on playing in the current build.
Research:
I know a lot of folks have been clamoring for multiple simultaneous research tracks to speed things up. My idea for research is to have the ability to research on multiple tracks simultaneously as a research able tech.
If you put the a research for the ability to research multiple techs in tier 2 or 3 it'd help with the issue of having a long backlog of researches late in the game. Maybe even going so far as researching 3 techs at once at higher levels.
This presents and opportunity to diversify the factions as well, maybe Advent gets the 2 researches at level 2 and Tech gets it at level 3. Alternately, they could make it so running simultaneous researches isn't as fast as running a single research and that speed can be improved by other researches. This adds a way to make the factions play a bit differently, maybe Advent is able to research multiple things simultaneously earlier, but the speed debuff for doing that is higher.
Orbital Mechanics:
I love the addition of the planetary orbits. It would be really cool if there were ways for the factions to manipulate the orbits of the planets to their advantage.
For example, if the Vasari got an ability to accelerate or decelerate a planet or asteroid's orbits, or change it's orbital distance to the star. In my craziest dreams maybe a high level ability you can use to collide one planet into another, ya gotta admit that'd make a killer DLC!
The tech could take up surface slots, so if you want to build a mobile planet you can't also have the garrison fleets.
What ideas have you all had for things to spice up the differences between the factions?
The orbital manipulation mechanic is interesting idea, that did not cross my mind.
Regarding research, as you say, perhaps unified lab for both civilian and military is TEC only thing. Other factions may still have this separate, thus having 2 simultaneous research tracks. Its definitely thing to consider, when trying to make factions more diverse.
On topic of my own ideas, my fav faction were always the Vasari, so everything mostly concern them. Recently i thought it would be cool, if they could harvest rare minerals from the sun via Orkulus. Like you would build Orkulus (or more of them) in star gravity well, near the sun, it would fire some kind of beam into its corona and keep mining stuff. So it would be ongoing process, that would add you one unit of rare mineral per say 5 minutes, unlike TEC approach it would happen for free, you would not need ore or crystal to refine this stuff from, but obviously it would happen slower...additionally it would be capped by the number of stars on the map, if you would play only single star map, then only single star for you to exploit.
Another thing, i always wanted the Vasari Loyalist mobility theme to be more fleshed out. Their Titan was supposed to be mobile homeworld, but it never really felt like that, aside of its ability to drop the phasegate and call in fleets via that. Now however, with the addition of components, this could be tackled... so i hope for strategic level stuff like colony pods to bolster your tax income, shipboard lab component (i suppose this will be capship component as well, it wont be single research to unlock it, now you would need the lab to "manually" upgrade on each ship you would want), another possibility could be built in factory to produce ships, broadcast center, some kind of superior planetary bombardment tool, built-in rare mineral refinery, its own built-in phasespace stabilizer similarly to Antorak Marauder, on top of the ones it can drop, etc... simply stuff that the thing would not be just teleporting manta-ray of doom like in the first game, but true mobile planet, keeping your economy, production and research afloat.
Finally, i was always bit disappointed, how Stripped to the Core ability worked, before Rebellion was out, i was anticipating the Titan would strip the planet. Eventually it would eat fleets, which was cool and i hope it stays, but if the Maw or some other ability instead of say Desperation now made it to strip those poor planets, it would be all kind of awesome.