Even more interesting, out of all of the years I've ridden with the ez endurance stirrups with plain ol' Nike's running shoes, I've never had a problem with there being too much grip. Been tossed a few times (horse zigged and I zagged) and never had a foot catch...
Could be riding style has a lot to do with it as well - if you are a rider who depends on your stirrups for balance every moment or if you are a ride by the seat of your pants person (that would be me) LOL! At least that's how I think I ride - after a hard spook or buck, I stay on, but my feet come out of the stirrups. Everything happens so fast!
Tapederos are heavy - I haven't seen any kind other than leather. I thought I heard a story about what their purpose was .... back in the western days, cowboys (vaqueros) or whatnot would rustle up cattle through the thicket (sometimes mesquite) and it would protect their stirrups from being caught on a branch and yanking their saddle while on a fast moving horse. Also worked well for winter protection in snow and cold.
I have a pair of the plastic/synthetic wide endurance stirrups, too - got them off of chick's saddlery or country supply or someplace like that - not as comfy padding as the ez stirrups, and not as pretty but they last forever. Probably weight about the same, tho.
Another interesting thing about the ez aluminum, is that the neck of the stirrup is held together by a bolt and can be easily replaced by any bolt from a hardware store so you can make them fit 1" english leathers or up to 3" western saddle fenders. That's a nice quirk!