I've never had an RBTA, but after several dozen GBTA's (clones of the same mother), they love to give themselves buzz cuts. I kept powerheads up high, so it wasn't as likely (though they still found a way from time to time). I never lost one to a powerhead, though. If you get ojne caught in one, just turn the pump off and let the anemone fall out on it's own, rather than trying to pull it out of the screen. I only ran MJ's, though, so Koralia's make a much easier target.
Mine never moved except for after a cloning, and the mother usually settled back into a location within 3" of the old location after coming back out from the rockwork. The babies wandered constantly, though.
The only coral I lost in 8 years of keeping BTA's was a hydnophora frag I got from an LFS meeting (probably EBay in the early days of the club). It got knocked down into the sand where the big momma was stationed and she quickly destroyed it. I had a good many others get hit when the anemones were wandering, but they never lost any tissue over it (just showed signs of stress in localized areas). That all said, I've heard that RBTA's can be more aggressive when it comes to stinging corals.