As a bit of an update on the magazine situation: I ordered a pair of 13-rounder P14 mags from Mec-Gar. I ended up chatting with Monica, who had the pleasure of being the only person in the shop on a snowy Thursday, for about 30 minutes. Nice lady, she is. Anyway, the mags arrived yesterday, and on comparison with the factory mag...
They're identical. The finish is different, since I ordered the nickel mags, and the factory mag doesn't have the Mec-Gar logo on it, but they're the same. There is some sort of maker's mark, it's a -A-, on the side of the mag body, and it appears on both the factory and new mags. The springs are identical, the followers are identical, and the floorplates are identical.
I think Springfield is going with Mec-Gar for their magazines.