I have 5 otos in my tank with a BR and a GBR. I'm planning on eventually getting 3 more GBR's. SO FAR, I've had no prob with my rams bothering my otos. That's just my experience though. When I get the new rams they may be total terrors to everything else in the tank. Who knows? Unless you want to try breeding shoot for all females to keep the aggression down. I have a thread on here "I want more GBR's" that touches on that.
BTW, I'm not trying to talk you into rams! I just happen to really love em.