I use the cheaper of the Endura ones, thermolite? anyway not the FS260 ones
I find if I overlap the legwarmers with my lycra (under/bib) short maybe a couple of inches they never slip down. If the leg warmers go over the lycra they always slip down
I like the zips to zip down over my waterproof socks and stop water getting inside them
tbh, unless its raining and cold, or sub zero I don’t use them (similar goes for my 3/4 thermolite bibs), they get too hot for me and I can feel I can’t get decent pedalling power
In anythign above maybe 5deg C I use the knee warmer versions which I find don’t get anywhere near as hot, but keep my knees warm in any wind/rain and offer a teeny tiny amount of abrasion resistance in minor offs