So I've had an assortment of rear lights over the years and I've ridden behind more than I can remember but other than something tiny like a little Knog Frog none seem very well suited to paceline riding at night. My local rides tell people to set their rear lights on steady when in the paceline but frequently they're still quite blinding. Especially if they're aimed too high or mounted on the back of a helmet.
I find this a big problem because I'm light sensitive. I have awesome night vision but I'm prone to being dazzled by really bright lights.
I obviously can't force people to buy new lights but I need to get some new ones (for the girlfriend's new road bike and to replace a few beaten up Superflash knockoffs) and I don't want to contribute to the problem when someone is following me. Especially as the GF has her new road bike and I'm trying to get her comfortable riding in close proximity.
Complicating things at least for me is that neither of the bikes have much (if any) seatpost showing once you put on a medium Topeak Wedge saddle bag. For my bike I clip a Blackburn Flea to the strap on the back of the saddle bag but I know it's prone to bouncing a bit and blinding riders. I'm thinking a saddle mount like that used on Fizik saddles would be cool but I prefer SI Flites and only Cateye seems to make a saddle rail adapter that I've seen. I can't stand the weight of a decent flat repair kit and multitool in my jersey pockets so dumping the saddle bags isn't really an option.