Any comparison using the same figures is OK in my book. I'm used to dBV and dBu for mic and audio equipment noise and sensitivity figures. dBV is an older value with dBu being more common these days in my experience. But both are valid and easily understood.

The Nu v2 is certainly quiet enough. Well below any practical audible threshold and well below most background noise levels. Normal electrical hum levels will be 33dB below an equivalent Strat coil (or will it be less if the Nu v2 figure is for a single pickup rather than equivalent 6 units?) and 22dB below a humbucker.