The biggest issue I see with weld on ones like that, particularly if you live in road salt country, if failure to clean them out regularly. The diff pans are pretty thin and it won't take long for them to rust through. That notch in the bottom isn't enough to allow self cleaning.

 

My front usually catches some of the spilling oil when removing the oil filter. I figure I'm safe from rust on that one. Whenever I change the oil, I take a stick, screwdriver, whatever and clean out the drain - it does get enough dirt in there to clog it up from time-to-time. But around here, the rust issue isn't nearly as bad as other parts of the country. It'll pay to keep an eye on it - good point!