My 7.9FX weighs 21 pounds if I remember correctly. My Giant FCR1 weighs almost a pound less. In comparison, the 7.5FX weighs 23.5 pounds. Lighter is always better, no matter what anyone says to the contrary. That being said, when dealing with flat bar road bike weights, it's more of a good, better, or best proposition. A few pounds of weight should not a deal breaker, or fun breaker, one way or the other.

PS: the benefit from the carbon fiber frame is not just weight. A large(r) part of it is ride quality.