Had an a&a aluminum drum in mine, no significant wear after five years of street/ race use. Rick at A&A said he had seen some wear in the sealing ring area of some of the trans' he had apart. He seemed to think it was a fluid related problem, because it was random. some had it, some didn't I always used redline synthetic trans fluid.
I also used this drum as a safety feature more so than for quick spin-up.