I own the 7.4 Disk and love it. The weight difference is negligible -- my own weight varies more than that from day to day. The disks have awesome stopping power that you will appreciate in those scary moments when you really need it. I've always hated fiddling with rim brakes -- the disks just work. And IMHO they look awesome.

Never had a bike with a carbon fork so I can't comment on what's given up. But I can tell you that the bike rides smoothly with the AL fork.

The color is a matter of taste. I like the grey and green. It looks much sharper in person than in the pictures.