pro's

50w tube, its easier to push the tubes into saturnation for that sweet overdriven tube sound

50w is loud enough for most practise stuff

cons.

50w might not be enough if you play really loud, I've gigged with a 60w top twice and it was allright, but I didn't have much of a reserve, that's where a 100w head comes in handy, especially if you have two guitarist.

Depends on what you're gonna use it for.