I had a Giant TCR A1 (carbon spine/aluminum) and didn't enjoy it, I always felt like I was dragging the rear end while climbing. At first I'd look back to see if I had a flat or some. Before that I had a Bianchi XL EV2 (aluminum) and it was magic but I could never get it to fit just right and was tired of sore shoulders all the time. I now ride a steel frame bike with very slack geometry and love it. I'm not suggesting you get a steel bike but rather consider your long-term ownership. As your fitness increases you'll undoubtedly want to test it with a challenging charity event or organized ride with ridiculousness mileage and elevation gain. If the geometry or fit is not right, I don't care if it's carbon, aluminum, steel, TI, whatever, you'll suffer needlessly and not perform to your full potential.
As far as longevity of materials is concerned, you have nothing to worry about. Average Joe's like us will never generate the wattage necessary to fatigue the materials we ride. If you can produce wattage equal to Cav and ride 25k a year, then you'll want a new bike every couple years. In which case, some team would be giving you a new bike every year anyway.
Lastly, I ride with a guy who's a retired pro. He rides a CAAD10 and said there's no reason to ride carbon for stiffness, the CAAD10 is the stiffest frame he's ever ridden and that he wouldn't go back. He still races masters and is deadly on it.
Good luck and enjoy the new ride whatever you pick up.