I've yet to take a collision on a bike that has one.
that's a strong endorsement of a relatively easy addition to any bike.
I, too find them somewhat unsettling ( I guess that's how I feel), as they are an unexpected sight, and so get our attention.
Whenever I share lanes on my BMW, I use the emergency flashers, and occasionally flip my high beams off and on to enhance my chances of being acknowledged.
I can't tell you how well it works, because I have never been touched by a car in 40 years of lane sharing. (except a couple of times when I ticked someone's mirror...my fault entirely, by the way).
I once followed a CHP bike from Rocklin to Sacramento in stopped traffic, and when I deployed my flashers after falling in behind him, he gave me a quick thumbs up in his mirror, so I will take that as a sign that it was a good thing to do.
It's a shame that all bikes don't at least have emergency flashers that could be used in this fashion, or better yet, a special Hi-Viz lens that would alert car drivers to a sharing rider in the lane.
I have often thought the ultimate commute bike would be a retired CHP BMW RTP. It would be like Moses parting the Red Sea with a 4X4.
Even the meanies who think it's funny to crowd the lane so that bikes can't pass in the shared lane will give way on the off chance that it might be a CHP.
Still on that subject, I did see a pickup truck deliberately try to block a lane sharing LEO over on 101 last year. He got exactly what he asked for.....stopped immediately.