*bump* to report that I'm a bit over 5000 miles on my Panasonic H27 hub. It's on my beater fixed-gear MTB, so it sees all of the winter riding and most of the rain, yet the bearings and electrics are just fine. It seems like I hardly have to move the wheel for the headlight to start flickering, which is great.
I knew going in that this hub would have more drag than other dyno hubs, but I'm not as weight/efficiency-minded with this bike. And since
the drag is hardly different whether the light is on or off, I just leave the light on all the time.
Here's a pic from when I had just built it up in Jan 2018:
