I know he did change certain things, but for the most part it's a reuse of an old sculpt. Personally I don't see the added $100 value despite how good it looks. I also know John isn't in this business just to make money and profit, that's been known for a while now. However it seems to me that he didn't expect his first project to take off like that and he saw how many people wanted his V1 sculpt after it sold out so he decided to reuse it. Then adding that extra $100 makes it seem like he's trying to profit off of the people that missed out on his V1.
I could be wrong though, these are just my assumptions. I don't talk to John so I don't know him personally like you do.
Who in their right mind would buy a sculpt for $500? That's pretty insane. I wouldn't buy anything of Ambrosial anymore just because of the fact he sold his sculpt to Hot Toys, which is completely ruined now. There's nothing unique about it anymore, I'd be pissed if I had done custom work on it.