Just my opinion but if you're planning to put the Wilson left hand safety on the SS, I wouldn't send it back - just have a local smith fit it.
As for the one that won't lock back on an empty mag, I'd first try a few other brands of mag, new and used, to see if the issue is with the mags and not with the gun. Since you said that if you rack the slide yourself on an empty mag it does catch, it almost seems like the follower is going too slow to beat the slide.
Eliminate the easy problems first before giving up your gun for who knows how long it'll take to get back from Taurus.
As for the one that won't lock back on an empty mag, I'd first try a few other brands of mag, new and used, to see if the issue is with the mags and not with the gun. Since you said that if you rack the slide yourself on an empty mag it does catch, it almost seems like the follower is going too slow to beat the slide.
Eliminate the easy problems first before giving up your gun for who knows how long it'll take to get back from Taurus.