Failure. Mine lasted about 5 months and after a one week vacation, body was never found. However one thing I wants to point out. I have same experiences with chevron too, usually lasted about 3-5 months and somehow died. I think poor nutrition, swimming space, and tankmates may have something to do with it.
Just before I converted my full-reef to the reef/seahorse mix tank, I have just acquired a chevron tang, just about 3 months before. During the conversion, I returned all big fish and tangs to LFS except the Chevron, thinking it can be a good helper in keeping the turf algae at bay. It has been about 9 months since I have that Chevron, it is still going strong. Full stomach without target feeding. Grazes all day with regular feast of live saltwater ghost shrimp. I have never seen a Chevron as happy as him. He is the only 3"+ fish in my 150.
I think PBT can also be kept if he has plenty of swimming spaces, occassional live feast, and absence of competition....... pretty much same requirement for all tangs.