I’ve switched back to only SS again. Factors include
1) easy conversion of existing wheels,
2) over 50 years experience with coasting and none with fixed,
3) I’ve been riding for the last few years on flat pedal without foot retention,
4) I’m trying to spend more time standing and this includes coasting downhill and
5) there are lots of sections of my rides where I want to stand and coast and negotiate challenging terrain and circumstances where I don’t want to also still be pedaling.
All that said, I have some interest in building wheels with wider rims to run 700x38 on my Schwinn, so I may build a rear wheel with flip/flop hub that gives me the chance to try out riding fixed.
Otto