I've often pondered the 'light frame lasting a season' question: my stumpie is tange prestige but has lugs and has taken abuse for donkeys years.
I've also heard that frames with short head tubes are prone to cracks as there is less to resist the leverage of the fork.
There is a custom (mountain) bike on here somewhere that was built of Columbus genius and seems to have stood the test of time.
Maybe the rigours of on the limit "ten tenths" racing are far more than the - say - "seven tenths" use of a recreational rider over a number of years?
But one question is, do frames that fail do so because of being too weak to cope with general riding-along stresses or because of crash damage (even if the crash was in the past and the breakage was a delayed-action)?
I would have thought that a frame that was too light to be strong enough to race without breaking it, would also be so light that it would be too lacking in stiffness to be a fast racer. Just a guess though, I've never seen any figures to prove it or disprove it.