Well I ordered and received 3 metalform mags from Champions. They were $12.00 each. When I first inserted them in the gun they didn't lock the slide back. I played with them a few minutes (pushing the follower down a fraction of an inch) and tried again and they now lock the slide back normally. I haven't had a chance to fire the gun with them yet, but I think they will work well. They appear to be very good quality.
I guess it all really depends on what you're doing with the mags. I've noticed several welded mags cracking after repeated drops from speed reloads. If the base is removeable, it's replaceable and cracking isn't a problem.
Cleaning is also important. Being able to reach ever nook and cranny with a toothbrush is important for longevity, if nothing else.
I just ordered two Wilson #47D mags for my SA and can't wait to put them through their paces. I won't throw out the welded SA mags that came with the gun (they're great for CC), but the new mags should give better performance, all things considered.
Given the choice, I would always go with the removeable base pad.