i've found nylon straps to be decent. certainly better than the low-end MKS single straps that i also have. the old, crappy looking nylon straps run through the buckle well, so tightening and loosening is a breeze, and they get snug. they don't always stay snug and i find myself re-tightening during a ride especially if i'm do any hard acceleration or deceleration. if i were currently futzing with a new clip/strap setup i'd probably get two pairs and run some bootleg doubles. i've done it before. the front one adds some additional security - it really does feel different, and quite nice - and the rear one can be tightened and loosened (i tighten every time i get on, and if i need to put a foot down, reach down and touch the buckle so that it loosens).

so yeah, i'd say that you can find a satisfactory setup with nylon straps.