Not a good choice for your tank.
1) tangs are grazers, and with all the frilly bits hanging off of a stonefish, there is bound to be trouble - either the tang gets damaged/eaten or the stone gets stressed constantly/damaged.
2) they demand great respect, and maybe you don't think experience counts for something - but believe me, it does here.
3) feeding - how experienced are you at training lion/scorp type fish to eat prepared? Granted they don't have to eat that often, but providing it live saltwaters feeders will get old quick, and training them onto dead food may take some time.
4) they are not interesting to the majority of fishkeepers/reefkeepers, if you are still considering fish like blue tangs, kole tangs, snowflake eels, and dwarf lions - you most likely are not going to be happy with (and are not ready for) a stonefish. Sounds judgemental, but what the heck, it's true.
BUT! on the bright side, I love the two I have and think they are completely awesome fish, beasty is the word, and very awe inspiring when they go for a swim...
good luck, whatever you decide.