So much faster/quicker, 6 lbs lighter
Hmmm. I think any bike that is 6lbs lighter is going to feel a lot better, steel, titanium, alloy or carbon?
Nice alloy is lighter and rides better than cheap carbon. Most of the benefits of moving to carbon can be achieved with a carbon seatpost, stem and bars. Wheels will make a bigger difference. Nice carbon however can be stiffer, will be lighter and may absorb more shock. I'm afraid nice carbon frames start at the £1K Bike to Work limit.
I ride top end carbon, alloy and steel. THey are all different and anyone would feel the difference. Geometry and fit are matched. But Son1's CAAD8 with some decent wheels and a carbon seatpost is a truly fantastic alloy bike!
EDIT: asterix, the owner of 700C in Windsor has a CAAD10 and a supersix (same geometry). He says apart from a pound in weight, he can barely tell the difference when he's on the bike. The CAAD10 is the best alloy frame available and trumps most carbon frames. The BB30 bottom bracket, however...