Cartainly an individual thing. I've seen it go both ways. I have a little trimac who has claimed his third victim in the past three weeks. This time it was a Jag that was larger than him. I have a few fellas in a grow out tank, but I think he's going to have to get his own. I know that aggression gets transferred to FH's, so they're probably nasty. I unfortunately know what happens when a monster FH and a Monster RD end up in the same tank (55G) A fella I know had a tank full of brutes and saw a FH at the lfs and had to have it (it was about 10-11" I think, Ry, you know who I mean, you know how big they were). Anyway, a ffew months later he saw a 11"12" midas/rd and ended up buying that out from under me. Iit didn't take long after the midas got used to his surroundings for him to beat the crap out of the FH. Both fish lived and he realized how bad an idea that was and gave them both to a lfs.
Just some personal experiences.