MM,
I have broken a few of the plastic straps in rough landings on racing planes. (Clown, Sport Goodyear) Never on a stunter. If you use them, you could also add some insurance by taking a wrap or two of malleable wire (stainless steel safety wire would be great) around both legs just below the fuselage. And don't forget to include a hard maple block or aluminum plug in the fuselage where the wires are inserted. More than one way wire gear can fail....
I always use two sets, but it's the bottom one that takes almost all the load and will break first. The upper one is there just to "get you home."
I couldn't bring myself to bury plastic clips on a Cardinal I built. So I made a cutout for the gear leg and the clip thru the outboard tripler.
Good luck with your project!
Dave