W_D is right, you definitely want waterproof gaiters for late fall/winter/early spring, but probably not for summer. I missed the year-around bit. Both Dirty Girl and Simblissity gaiters are non-waterproof fabric, made for summer hiking (not for rain, snow, cold mud).

I also prefer the knee-high gaiters for snow, and mine are also from OR. Too hot for summer, though.

My main use for low gaiters is to keep the bugs from biting through the upper part of my socks. Also, if sprayed with permethrin and worn over your trouser bottoms, they keep ticks from crawling up your legs. For those purposes, fabric gaiters are fine. Outside of bug season, though, I don't wear gaiters unless there's snow on the ground.