Depressing answer is: no, not really. Spend a couple months grinding away, drop millions of credits and other resources, and then not really much there. really just doing it for the skills/powers, IMO. I unlocked both on my primary a while ago, and other than getting the Adapted MACO set and some different costume tweaks, not really much there to buy. Haven't even played him in a while, as he's maxed out with nothing to do, and no incentive to do anything...
Well you do get a decent amount of dilithium from the Romulan rep and you can unlock the Reman race for the upcoming Romulan faction no matter which faction a character that completes it is in.