I actually went the other way. Was going to go with the Expert Carbon. Took it out and then took out the Comp Carbon. Riding on the flats and gentle rolling hills in Illinois I couldn't tell the difference...not in stopping power and not in shifting speed or crispness. The brakes for a rider my level felt identical...perhaps if I was heading down some mega mountain I'd notice. I was still going to go with the Expert but they gave me $200 off the Comp which was in stock (Expert I took out a size smaller and would have been ordered). It was a no brainer to save the cash on something that I would never notice.
On top of that...not sure if you're like me but I already feel like I'm going to ride this season and then go to a road bike after that. I have the itch to keep pushing faster on each ride and go further. Not to down sell you but I also felt that the higher the initial price tag, the bigger the depreciation when selling. I'd ride both and truly see if you can tell the difference.