Cyclocross is a gruelling contest of rider against rider, rider against the course, and rider against the elements. As such, a number of factors have to be considered when designing and building a custom 'cross frame: rider physiology, mud clearance, portability, light weight, extreme strength, and sure-footedness. All of these are essential in delivering you to the finish line. Still, you need to supply the legs and lungs!
Cyfac has made cross frames for French national team riders, European national champions, and various World Cup stars. Before cross became popular, Cyfac was making frames for pros to use during "off-season" training. Cross has been a mainstay of Cyfac's business whose builders have been tearing it up on the French and international cross scene for upwards of 20 years.
Like any of Cyfac's frames, their 'cross frames are available 100% sur mesure--made to order. You want full carbon, no problem; you want scandium, aluminum, or steel, you name it. Cyfac's "production" frame is made from 6000 series aluminum and comes with a either a carbon-bladed/aluminum steer tube fork, or a full blown monocoque carbon fork, replaceable derailleur hangar, and Stronglight headset.