After my rear wheel on my daily bike began to 'dish' after 3000 miles I am going for Disks simply for maintenance and longevity reasons, as well as wet weather performance (I get pretty fed up when my wheel, tyre, guards and clothes get covered in black brake grime!).
Plus off road snippets down old railway lines etc is much more pleasureable without the grinding noise of pads against a wet gritted up sandy rim
As for the genuine road benefits. Reduced rim weight is a potential benefit without sacrificing braking performance on a carbon rim.
I think I would rather have carbon rims with disk breaks on a long decent rather than using rim brakes on a full carbon rim, I have seen a hell of a lot of de-laminated carbon rims from long descents.
Avid are already bringing out a lighter weight version of their BB7 for road specific use in 140 and 160mm.
The big boys, Colnago (new C59) and Cannondale amongst others will have done their testing I am sure. Their reputations are too big to be tainted by doing something which isn't 'right'.
Hydraulics are already an option too. Hope do a Drop Bar kit, as well as TRP with their Parabox set up.