FWIW the Fly6 is now down to $120 on Amazon. I have one coming. ISTM that a 5+ hour battery AND it's what looks like a pretty good taillight all in one for $120 is a heckuva deal.
I do need to work out mounting for days when I have the rack trunk bag on, but I have a 3D printer, so that won't be an issue.
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Work: the 8 hours that separates bike rides.