I've shot a few thousand rounds of 6GT using that magazine technique with only maybe 1 or 2 issues over a bunch of matches. My strategy is to always have a spare mag in a holster loaded with 10 rounds, in the event of a mag issue I just swap the mag on the clock.FWIW on the mag followers:
I have both types, and they feed 6 and 6.5 CM flawlessly...but both will cause the 6GT to nosedive in the mag. I think I shared a picture of it in here before, but I can attach another one again if one wants to see the end result.
My workaround is to load the rounds forward, where the shoulder of the 6GT case is even with the front of the feed lips. It works for static firing, but I don't think it would be very effective in PRS.