This is a great bike rack for people who are looking to carry two bikes using a hitch. I had an older bike rack from a relative but my MTB had fallen off of it once already, and I bought the Kuat as a replacement after doing some research. I usually carry my road bike or my 26" MTB on it - haven't tried a 650B or 29" bike but I do not foresee any problems making them fit on the rack. The loading process is quite easy, and the bikes are securely held using no frame contact at all.
The rack is quite light due to the aluminium construction, but sturdy at the same time. The adjustable anti-sway cam system in the hitch mount is great, and reduces the swaying that bike racks are subjected to - but does not completely remove it. However, I'm quite confident in the stability of the rack for long-distance driving or on rough roads. I have to drive on a few kilometers of rough fire roads before I can get to the local biking area, and the rack has not caused me to worry about my bike falling off the back - unlike my old rack!
Issues with the rack - the rack could not tilt for storage properly on my Subaru Forester (2010) due to the hitch receiver being recessed underneath the rear bumper. I see this as an issue that could occur on vehicles with a "hidden hitch" design, such as smaller sedans or SUVs. What happened was that the closer front wheel carrier would bump into the bumper, preventing the rack from folding properly. 30 seconds with a sawzall solved the issue - I trimmed the plastic front wheel tray 2 inches to allow for clearance, and now the rack works properly. The QR for the folding/tilting mechanism does squeak quite badly, but I think this will be resolved with time/a bit of lubrication. The locking system is a bit less desirable than the NV's built-in lock, but the included cable lock is at least thicker gauge. The lack of ability to add a 2-bike extension is also quite unfortunate, but understandable.
A great rack overall!