I think out of all the gigs we've played (which is easily in 3 figures I reckon) we've only brought our own amp 5 times.I'd say amps were unnecessary - might be nice, I guess, but I know I wouldn't want to practise with a different amp to what I'm used to especially if it's a Bogner or Dumble or summat and then not be able to have it when I played a gig, which I expect is what people practise towards.