I have a Boardman CX Team and so far it has been brilliant (on the tracks, towpaths and roads). The disk brakes have been valued on most of the wet days we have had this month. Highly recommended.
Genesis Croix de Fer is a good bike. I have the 2011, but the 2012 comes with BB7 discs, or the (Aluminium) Genesis Vapour would be a wee bit lighter, and the 2012 also has disc brakes. There are good deals to be had on the 2011 Croix de Fer
My colleague is looking at the Planet X Carbon (yes, carbon) dirty disco CX bike, but at £1500 I think this is too much for this type of bike
I dunno, Dirty Disco looks like good value to me... I guess it depends what premium you place on weight
Realistically, if you're looking for a race bike, then the DD is just about the only disc equipped offering out there that will be competitive. Add a pair of Major Tom's and you're good to race.