Only thing more fun than a hoax is the people who think it is one.
No offense... but someone needs to listen to the Castato guys. They're a trio. NONE of their material (I've got all 5 of their releases) sounds even remotely like Art Jackson.
More importantly... I asked them about it. They said "definitely not" and said they got the links and information from a blog called Never Get Out Of The Boat, who is no longer running the links. I've yet to hear back from them about it.
I don't know if Art Jackson is a hoax or not. But more rumors aren't going to get to the bottom of it.