In reply to MtnGeekUK:
I do! I have a mutant 38 (like it,) and have used it for 5 day climbing trips, so don't see the point in anything bigger. The mutants brother, the varient has a solid back and the mutants is a bit more flexy, so try before you buy. Before that I had an old incarnation of the Berghaus Arete 45 which was good too.