[MatrixClaw]

Out of both of those, I'd say the Mesa is the higher quality piece of gear. However, the Classic 50/50 is going to be loud, which I'm not sure if you'll need or not. The Mesa will sound great, but if you're going to be pushing it almost full on at gigs or practice and need it tight for when you're playing metal stuff, I'd probably go for the Peavey instead for the extra headroom. The powertubes will start to saturate too much on the Mesa and most likely make it sound quite a bit looser.

I'm honestly not sure the price on those used, depending on your budget there's a used Mesa 50/50 over at the Harmony-Central forum for $500 I believe it is. Not a bad price, and that's something that will last quite a while.