Well, that's totally different! lol

What kind of rocks are we talking about here? Tiny aquarium pebbles or rocks you can skip water with? At any event, you don't want rocks of any size wedged between any tracks, period. Just be cautious when you drive and let off the stick if it locks. Either tracks would do well as far as riding a linear path on small gravel... turning or sharp turns, that's where the problems begin.

Anyway, plastic vs metal tracks are a preference, not mandatory. Many people have driven their tanks stock with plastic tracks and seem to be fine with that.<br type="_moz" />