Thanks for the replies, people. Deciphering material specs is a little tricky.

So is pricing. The Gutterball is going for CAD$850. I've read posts on here discussing bikes for under $500. In Toronto I just don't see those prices. Things seem more expensive here, for some reason.

I'm looking at:
GT Gutterball - $850
Kona Paddy Wagon - $700
Urbanite custom frame - $900
MASI Speciale Fixed Drop - $950

I've tried all four, and for some reason kind of prefer the Gutterball. It feels really fast and responsive. I've test ridden it a couple of times now. Also, it seems easy to maneuver. I feel like I can go down steep hills and make quick turns on it.

But, based on everything I've read, paying that money for an aluminum frame was seeming foolish. Also, I've noticed that it isn't a popular bike. I've only found one store that carries it. That puts up an orange flag.