I've ridden 3 frames this year, all old but part of my road cycling learning process. First was an old Cannondale R500T aly frame. Was rock solid and super stable down hill but transferred a tremendous amount of vibration through the frame. I could only hang of for sooo long. Next was a Giant Once also aly frame. Was nice and lightweight but very flexible. It gave a smooth comfortable feel for distance rides but took me into an insane speed wobble each time I neared 55k/hr. I've just purchased a 5 year old Giant TCR C2 carbon frame and WOW.... everything about it is just fantastic---logically considering what I'm comparing it to. It's light, feels like it want's to pull me through the bends, ridgid and extremely stable downhill and super comfortable on the rough surfaces. Apparently the carbon as a rule of thumb gives you a stiff frame but with the cussioning benefits of a flexible frame. I wouldn't cry about a few grams extra weight between frames. Ride the option you're looking at buying and base your purchase on the feedback and feeling you get whilst riding.
