If you succeed in creating a kind of F&E mod for Sins, I just might buy some memory so my game computer can run it! My game machine is old, and only runs SFC and Baldurs Gate. It has 512 Meg Ram. I did buy a vid card to play Sins, but the small memory makes it too slow to play. I'm not willing to spend much on the machine at all. Perhaps I'll buy a Linux machine and run Widows emulators this Spring.
If this is what the models are for, the low polies are probably a good thing. The games sucks up a lot of resourses. Your models look good. You are quite right to limit the quality; these are not for the cinema. For this kind of game, models are little more than icons and shouldn't go much further than representing a ship's class. Each class should be distinct, and should not get bogged down in varients.