De Ver is my all-time most disliked bike shop on the planet (plays idly with box of matches and reaches for alibi). If I see someone on the road in a De Ver strip I have to overtake them, and that can be hard work on the Brompton. Seriously, though, I'd never go through the door. Except in a truck.
Brixton Cycles my (second) favourite is just down the road, but if you want good advice at that kind of money then Luciano's at the Junction is hard to beat, provided you speak to the proprietor.
And I wouldn't go for the Colnago. I think that every time you walked past it you might think you've overpaid for Taiwanese OEM. And you'd be right. Actually, Colnagos are for middle-aged geezers in flashy shoes with more money than sense.
I'd consider the Dawes Torino (all carbon, although not very light) with Shimano 105, but, to tell the truth I'd give Lincoln at Brixton Cycles a call and ask him if there are any Specialized bargains available, or go to Lucianos and ask about the Trek 1.9 which is aluminium with carbon forks, fitted out with Ultegra (watch our for dodgy ratios on the cassette) and Bontrager. And Lucianos will have a Kuota Kharma, which is over your budget, but pretty darn good.
The advantage of Trek and Specialized is that they make their own frames, and their research is continuous. They don't wander around Taiwan every year looking to see what they can re-badge. And their buying power is tremendous.
Oh, and just to prove that there is no real pride in purchasing a bike I'd speak to Matthieu at
Evans (!) at Clapham North and ask if he's got a bargain he'd recommend. I'm sure there is absolutely no truth in the rumour that Evans are having trouble shifting bikes and are discounting furiously, but it doesn't hurt to ask.
And to go back to where we started. One of the most important components of the bike is the service you get afterwards, allied to the honesty of the people selling it to you. I reckon that paying a small premium to an outfit like Brixton Cycles is worth it, if only for the quality of the after sales service.