Yes, I have seen the Fallbrook tech literature but considering it comes from their internal engineering dept. I would hardly expect anything different.
That's why I asked about either anecdotal or better yet empirical evidence. The Ebike
site I linked is one of the few conversations on this I've encountered.
On another motored bike forum, a well informed user when asked about the NV confirmed a fairly substantial power loss, in his estimate 25%. He seemed content to live with that however,
explaining his setup is primarily useful in low end torque in the off road riding he does and he
is running a fairly powerful motor.