I currently use Hash AM and its about time to upgrade (Mine's 4rys old). But it looks like Softimage XSI is only a little bit more. Just wondering if anyone had any opinions comparing the two tools.

Well, you don't see a lot of people using A:M for game work, which is probably why nobody's answering your question. It can certainly be done, though -- Tak and its sequel are good examples.

For (pre)rendered stuff, A:M comes with hair and cloth sim -- which the low-end XSI doesn't. The cloth tests I've seen from v12 are looking really nice, FYI. On the other hand, XSI is a more mainstream product, and its pricing structure is likely to make it increasingly popular. If you want something that'll look good on your resume as it does on your demo reel, XSI might be the way to go.

I'd try the demo before I committed to anything, though.