Chris, I agree that some of the plastic clips break, but I've also have a bicycle messenger bag that I've been using since 1988 with the same type of plastic clips, and have never had a problem with them. Also had them on my old Tamrac 608 bag, bought in 1993, which I completely wore out, but the clips on that never broke either.
Hoping these last a while, but if not, I'll just put on a new set.
Best,
-Tim