i don't know a while lot about them but i did do some research on them because i really wanted one as well. some things you should consider. Live aquaria says they can get up to a foot and i was concerned it would take away a lot of room for my corals (i have a small tank). They can easily sting and damage corals.
I'm not sure the exact requirements as far as light goes but i know its high. You may have enough with 5.2 but if the bta doesn't have enough it may roam around more trying to find a place with better conditions again posing a threat to corals.
You know your tank better then anyone so i will just mention this as something i've heard. They do require very good water conditions as well as stable. I'm sure yours are fine but usually they recommend a tank that is a bit older then your just because they don't fluctuate as much. So you may want to have the LFS
hold it for you and measure your water every day for a week or so and see how your tank is doing.
Hope that helps. if you get one you better post pictures for me cuz i love the RBTA's. I was currently living through ziggy's rbta since i can't have my own.