One thing I've found with luggage, hard or soft, one persons view is often argued by another persons view.
I'm in the camp where there is no right and wrong, just the luggage that you need for the trip you are taking, sometimes a soft bag, other times a hard pannier. I have the TT Zega, which I like, I also have the Oxford panniers (as yet untested) as well as some HG throwovers and Kriega US20. All have their uses, and all have their faults.
Welded panniers will be tougher, but harder to have fixed, whereas riveted panniers can easily be fixed with some small bolts if needed. Welded will be (or should be) better at keeping water out, but then it depends on other seals too. What I'm getting at, it's down to the overall quality of the build.
If I were planning a long trip today, on rough roads, then I would take a look at the Magadan Panniers from Adventure Spec here ->
http://www.adventure-spec.com/defaul...-panniers.html
I've rejected these over the Oxford panniers because of cost, I am unlikely to need the features of the Magadans and so the �230 difference isn't really justifiable.