Aren't big frames generally built with heavier tubes? (Or, at least, not built with lighter tubes!) My most lively rider is a 62cm Jim Holly Griffon. I asked him about the bike and he said it was built with Columbus SL, which he would not normally have used in such a large frame. (Perhaps the client was tall but light like me.) My guess is the lightweight tubing has something to do with its attractive ride quality.
David Bean Arlington, MA USA
(but in sunny and warm LA, where I had a great 45 mile ride down to and up and down Palos Verdes)