I don't compete in IDPA but I do in USPSA steel challenge and "action shooting"(?? Whatever IPSC turned into)
I use a CMMG guard 8inch with my DIAS. I can only run it in semi during the matches (as per the USPSA rules) but one day I'll make it to a subgun match..
I use the Hyperfire Hypertouch auto trigger pack. Switched out to an H4 buffer to increase my bolts dewell time which flattened out bullet trajectory (yes it makes a difference), switched from the factory break to a comp, and sometimes use a C-more or an Eotech. I've run over 1k rounds between cleanings without any issues at all, have around 5k through it in total.
And yes it takes Glock mags and has last round hold open. It is wicked fun.