Being a brain in a vat doesn't imply much though. I mean, you can't assume someone has lobbed your head of and crudely crammed it into a jar of formaldehyde. For all anyone knows, you're in The Matrix instead. So unless we constrain the problem, there's no more reason to assume it is torture than there is to assume it is euphoria.

As such, there are no implication to being a brain in a vat other than the fact that you don't experience the outside world. It says nothing about what you do experience. And it certainly does not imply permanent damage in the same way that death does.