Finally got the Commander out to the range again today. I ordered five 9-round Mec-Gars and two 10-round Mec-Gars to go with the two OEM Checkmates. Shot 209 rounds of Magtech/S&B/Prvi through it. No problems at all. Brings round count up to 359.
I did adjust the grip safety tension on the mainspring for more tension though. I think I'm going to ditch the ambi-safety for a Wilson standard, some Hogue panels, and leave it alone.