I would rather, by far, have a Proof Research barrel on a 3 lug (Rem. 700 compatible action) in a stock or chassis of my choice. The Nucleus action is my first choice of this 3 lug bolt style with a Remington 700 footprint.
Choosing a PR barrel is because I much prefer the way Proof Research winds their graphite strands onto the barrel with a "Maypole" style overlapping diagonal web that is THE most uniform way of doing this. Plus PR uses Bartlein barrels.
As you can guess, I do not prefer either the Christensen Arms or Proof Research 2 lug bolts. But if I had to choose a ready-made rifle with a CF wrapped barrel it would be a Proof Research rifle for the reason stated above.
Eric B.