It doesn't really work like that for me. I've enjoyed the current Deep Purple lineup live, but it wasn't the kind of revelation that would make me go out and look for their latest albums. It was just a welcome change from some of the disappointments (Genesis, Canned Heat, The Yardbirds, Robin Trower). Somehow I didn't take much notice of Mountain first time round, so seeing them last year was more like discovering a new band (and they were great). And then there's Dr Feelgood, which I really didn't like at all originally, but the current lineup is one of my favourites to see live.