I have a STI Spartan 1911 in .45, their entry level pistol. It has never failed to feed factory ammo of any sort. The rare misfeed was my reloads and on checking the round I found an issue with the problem round. I need better QC
And yes I use a shock buffer. I do use Wilson Combat mags, mainly because I have had good luck with them and so did a couple of my buddies with 1911's.
I know several shooters at my range with various models of STI, from my entry level to the @$3699 GM model. Everybody has put out positive feedback.
Unfortunately everyone puts out the rare POS product. Sounds like you won one from STI.