Only .3 watts? I don't know the SA hubs but I would have thought closer to 3 watts. Or is that a slip of the finger?

FWIW, I have owned and used intermittently a Union bottle generator since maybe 1974. It has always put out plenty of power, created a noticeable but tolerable bit of drag (wouldn't want to run a century with it!), and made some noise. It seems to have developed some wear in the bearings which allow the shaft to move in and out some. But it still works.

A few years ago I built a wheel with a a Shutter Precision SV-8. It drives a B&M headlight and taillight. Awesome device. The light flutters at walking speed (the SV-8 is not recommended for lower rotation speeds), but on the road it just works with no apparent drag. The lights just come on, end of story.