I have 2 together (clown & humu-humu) and they do just fine. The clown was added second, but is twice the size. They are in a tank by themselves w/ a large lionfish. I have thought about trying them in my reef, but then I watch them for 5 minutes, and only imagine what devistation they would bring to my corals.
As for the type you are thinking about, any "trigger" in my opinion would mean trouble for a reef.
I am definitely not talking down the trigger though, I absolutely love these guys. Great personality!
Hope this helps