Soon after @ColorFabb released their flagship (in my opinion) filament, the XT-CF20, I got a few spools to test it in our coming product to be commercialized in few days from this date: a new drone racer with dynamic titling arms and mostly 3D printed with the XT-CF20.
Find info on the development on RCgroups.com forum and in the official product web http://www.tiltdrone.com
The XT-CF20 is a blend of the Co-polyester filament called Amphora 3D from Eastman Chemical and chopped carbon fibers (not less than 20% of fibers). During the material research and testing for our drone, I got other carbon fiber blend filaments like ABS-CF and PLA-CF from other brands and I must say the XT-CF20 has the proper stiffness, toughness and manufacturability properties. The latter is especially important because unlike the XT-CF20, the ABS-CF and PLA-CF are very rigid already before processing therefore, I had serious issues when printing with them as they didn't allow much flexing of the filament and broke several times in the middle of prints. This didn't happen with the XT-CF20 at all, not a single time.
The extrusion of the XT-CF20 is a bit special though: first, Colorfabb recommends using stainless steel or hardened copper nozzles because the CF fibers wear the typical brass nozzles. Second, printing on nozzles with 0.5 mm bore or smaller provokes that sometimes the material gets stuck in the nozzle. Use 0.6-0.8 mm nozzles to avoid that. You can still print on 0.4-0-5 mm nozzles but you might get bad areas in the print due to some difficulties extruding.
I've been using the max temp recommended by Colorfabb: 260 degrees Celsius. Lower than that is supposed to work too but I didn't get good results. Probably you can print at 250 or a bit lower in nozzles of 0.7-0.8 mm since the material has less difficulties to flow through it.
Surprisingly, the XT-CF20 has almost no warp (the part in the pictures below is the main drone plate: up to 8 mm thick part and almost 30 cm long) even at just 60 degrees bed temperature. I like it a lot, so much that I haven't print with PLA and ABS since I got it, even for random parts, I use this filament or plain XT (which is softer than PLA and ABS but very easy to print with and good mech properties in some of my other applications).
Summarizing, I strongly recommend the XT-CF20 but first, get steel or copper nozzles of proper bore size.