I run one on a Giant Twist/Lite, an electric assist which I added a XtraCycle kit.
I've gone through several hubs on that bike. Because of the added torque from the electric motor and the weight I put on the long tail very few hubs were able to survive (cracked a SA-8 in half). The NuVinci has been the exception. I would expect it would stand up to the rigors of a motorcycle. Solid as stone and whisper quiet (and no click-clack while coasting). It is heavy but if weight is not a huge factor on your build it is the most resilient hub I've ever owned, even comparing it to several Rohloffs I have.
When you have it built up I would recommend double crossing the spokes. Triple crossing (at least on 26 inch wheels) puts the spokes at a very sharp angle. My Rohloffs are double crossed and have held up very well.