In reply to nniff:
Thanks for the link.
Interesting... The carbon frames do not bend as the aluminium do at lower loads in normal loading conditions or areas designed to take those loads, they burst completely when failure loads are exceeded, as you can see in the test.
Point loads however, in areas which are not designed to take those loads can well exceed failure forces on the carbon and it will shatter like glass (my case- expensive bike hitting a rock) where as aluminium will bend, so the aluminium bike will still be rideable but with an ugly dent.
On the other hand you can repair carbon fibre, though not sure how reliably, by slapping on some new carbon fibre. The replacement parts are much more expensive than the aluminium counterparts.