I too have the waterproof panniers from Nashbar and found the rivet attachment to be the weak link in the design. Like KonradNYC, I removed the rivets (tedious job), added small squares of Lexan for added support to the pannier plastic backing, and replaced the rivets with screws. Now the hooks on the bag will not pull through. After this upgrade I think the bags are very good for on-road touring and I have been using them for several years now on commutes. If you plan to do any off road touring or plan to ride on very bumpy terrain, then the attachment system is suspect.
If looking for economy panniers (when compared to Ortliebs), I think I would try Axiom's Typhoon panniers next (about $80 at aebike.com for a pair).