I used to have a bicolor dotty, but not any more. That's because it pestered the h*** out of my six-line wrasse. Basically, it would chase him away out of ALL of the rockwork, so that he was forced to hang out up near the overflow box, and at one point got sucked in though I was able to rescue him in time. So I returned the dotty to the LFS.
Yes, it would probably be the other way around. However, orchid dottys I hear are less scrappy, so you could give it a shot if you don't mind the prospect of tearing down your aquarium to retrieve it.