We recently built up a Look X85 Cyclocross Frameset.  Here are my thoughts after 400 miles and three races:

Specs: SRAM Rival, Deda Aluminum cockpit, BB7 SL mech brakes, Notubes Iron Cross Wheels, Specialized Terra Pro tubeless setup, Thomson 27.2 seatpost, 39 up front, 12/28 in the back, Ritchey saddle (still waiting for Bri-Wear saddles to come out), k edge outer ring

Pros: Bike was super light (at least for me) weighing in at 17.8lbs pictured.  It was quick, responsive and I had no mechanical problems.  I was also impressed with the tubeless wheels.  I think it’s a viable option for cyclocross racers.  The medium fits small for me and that’s how Look wants it.  This isn’t the 675 or 566 comfort fit.  Think 695 for cx, super aggressive.  It wouldn’t be my first choice for a 100 mile ride, but for cyclocross racing I thought it was ideal.  Sometimes Look gets a little proprietary and with the X85 it’s refreshing to put your own more traditional components on board.

Cons: Seatpost slippage, had to shim it a little bit to stick.  Disc only option forced me into the disc realm but it would be more viable with a non disc option.  This won’t be a bike I want to ride this summer on Montana dirt roads.  It’s not super comfy and I’m still not 100% sold on the paint durability.

Neutral: I must say I felt cool on the disc brakes, but I really didn’t notice any stopping difference from my TRP cx8.4.  The mechanical brakes were sweet for my limited mechanic skills.  I was able to make adjustments super easy in really bad conditions.  With 2014’s launch of cx bikes it looks like traditional options are less and less prevalent.  So no matter what your opinion you better start stock piling wheels.