Hi,
I think like many of the Acanthurus tangs you can get some hardy ones and some not so. With many of these fish, it seems to be more dependent on the individual than on anything else. Some will make it and flourish, some won't. I just got a nice big powder blue, he is a great fish, nice and fat when I bought him, I watched him for a while and he looked very healthy. Sure enough, he is going beautifully. Also, you'd need a pretty big tank for one, I wouldn't put one in less than a 6x2x2 for a small one, and nothing less than 8' for a larger one.
HTH,
Tom