Breen isn't worth it, but easy enough to collect, probably a decent set to grind on as you level up, although you'd have to KEEP doing it, as it's another one that sets itself at the level you are when you pick it up.
Not sure that works, as The Breen set is only unlocked very near level cap. I think you get the Jem'Hadar set earlier, bust still pretty close to endgame.
Is there a set that you can get as early as mid levels anymore?
Edit: That assumes you are not already Vice Admiral when entering Romulan Space...