I've noticed that some corals are very sensitive to being stung by the BTAs and some are not. For example, some acans and palys (nuclear greens) seem to handle frequent brushing by the BTAs just fine. I also have an ugly blue polyp monti that was constantly being touched by the green anemone and it didn't seem to burn either.
A red micromussa that I have, however, gets burned badly along with most other corals. That's why I have all the anemones on a central pillar/island in the middle of the tank.
Whenever I add a new anemone or if I shift the rock or lighting, there's a chance that the anemones move around. Once they settle in though, they seem to stay put.