I've had a Bontrager Flare R for a couple of months as a daytime light.
I have mixed feelings about it.
It has four modes - two daytime very bright modes, one flashing, one steady, and two less bright nighttime/battery saver modes.
It is ferkin bright in daytime mode, and would cut the mustard as as fog light in either of the daytime modes. The switch is positive, and the charging port does semi to seal nice and positively. The battery life seems good enough for me.
But
The supplied mounting options are pants if you've got luggage, and don't want to attatch it to your clothing - after market brackets are available but are a) expensive & b) made of cheese.
Its also an expensive light, if you can run to it the Dinotte 400 is probably the one to go for, if not then the Smart R1 (or clone) are very good (and I've never broken a bracket)