I picked up a SRAM T3 hub from an abandoned bike and installed it on a Dahon. I've ridden coasters very briefly on holiday but never looked at the mechanism or taken on apart, until now. So I've just been examining this hub and the design strikes me as weird. The brake shoe thingy could have just a little more clearance from the shell than they seem to such that there's not a constant drag between it and the hub shell, which there seems to be. It looks as though the brake shoe thing is more held in place by the shell than by the coaster mechanism, which mainly prevents the shoe from rotating... seems like this could be designed better.

Are all coaster brakes created equal and what sort of efficiency loss ought one to expect?