Mine is newly built up now.
I have put together a bike (now my only mtb bike!) to concentrate on self supported / going long events for the foreseeable future (BB200, Highland 440-530 etc) and with the help of Kemo M172 now powers the light and satnav.
When it was first built up I thought the hub was borked as it was so so so clunky when trying to spin it in your hands (I fact I actually rang up Exposure to enquire about it!). However, once fitted with a QR into the forks it spins fine. If you spin the wheel unweighted in the forks it just get very slightly clunky when slowing down to a stop but once weighted (i.e. in proper riding conditions!) you don’t notice it!
Went for a 4 hour ride at the weekend o shake down the new bike and it worked well. The hub charged the GPS and at the end of the ride there had been no reduction in the level of charge in the unit.
Will be taking it out on a night ride this week to see how it works in the dark!