I've been all over Don Cossack for this for ages. The only slight doubt is whether Vautour is up to running a big race around Kempton. I also reckon he has stamina doubts, but he'll surely be ridden for the trip which negates some of EC's theory. If he's going to get it it'll be a flat three miles around Kempton rather than a stiff 3m2f around Prestbury Park.
The other thing that I'd say against EC's theory is that all of us would have put Kauto Star in the same bracket when he was stepped up to three miles. The difference here is that Vautour is bred to stay it and Kauto Star wasn't.
I agree with Grassy with regards Cue Card. I love the horse, but just look at what he beat, albeit impressively, and I see him falling short. Silviniaco Conti is a horse I've never really taken to if I'm honest. He'll be at his best on Boxing Day, but I can't see any bit of form that's good enough to beat Don Cossack if he jumps the way he usually does.
Don Cossack has all the ticks in the boxes and I'm pretty confident he'll win, but if Vautour proves me wrong I'll get my money back on him at Cheltenham.