Pretty fast upto about 4" maybe about 1" per month then it slows down abit and they max out at 6-7"
I wouldnt put them with rams as they are much to agressive for them, and i mean MUCH to agressive
The cons would pick on the rams from day one...no reason needed.
As for not liking because of lack of color...obviously you haven't really seen cons in person... and even if they were plain as hell...the personality would make up for it.