I'll second most of the comments, but wouldn't get one unless you have a large tank... It's actually half the reason I'm upgrading my tanks this winter....
I have a Rose BTA and an orange one that I've had for 5 years now. I can't bear to part w/ either, and quite frankly, they've cost me well over their cost in corals and frags. The Rose took to wandering for a while, and started up again after it split last year.. I actually came home and found it on the front glass a couple days (yes, I was looking at the bottom of it's foot!). The orange one doesn't move too much now, but it's tentacles are very long and wavy (looks more like an LT anemone than a Bulb Tip). It also kills anything w/in a 12 inch radius! Literally. I've tried adjusting powerheads, changing flow, building rock sheilds... if it smells something near it, it kills it. The Rose has take to the high ground lately, and easily killed off a half-dozen frags, not to mention beat up pretty badly some of my more prized corals.
There's just not enough room in a 90 for two Anemone's and a boatload of corals. That's why I'm getting a 200
Regardless, I no dout will end up facing this difficulty a second time, when my 200 gets packed full, something splits, and decides to go walkabout.
If you don't have any now, and were just "thinking" about getting one, I'd say shy away. I've always been attracted to the clown/anemone thing, and have had one for 5 years... Can't stop now. But if I had the choice of getting into them all over again, I don't think I would. Just too much to lose in a twig tank, and not a damned thing you can do about it.
- Mac