I've never ran a 575 so I can't say from exprience. I've always been under the impression that the 372xp had just a little more ump then the 575.
My stock 372xp was nothing the saw my muffler modded 7900 was.
After a mild cylinder port, exhaust, and timing advanced it's close to the power the muffler modded 7900's are, but it's not beyond by any means.
I've never had a 32" bar on my 7900, but it runs a 28" easily. It's not too far from my stock 066 IMO. I think the 7900 wouldn't have any problems with a 32" bar in hard wood. I don't think it's going to be the fastest, but it's not going to be the slowest either.
I'm a Husky fan, but I'll be the first to admit the 7900 is a bad-azz saw.