I'm about to remove mine. Ordered a bypass from Saber Tactical and it arrived yesterday. "Delete" is such a strange word that people started using for the procedure.
Anyway.... The first reg in the M3 is really a hair-brained idea, IMO. It's very limiting since you're supposed to keep the regs at least 30-40 bar apart from each other. I could see some benefit if running a 300 bar fill, but at the standard 250 bar it really makes no sense to me. And my first reg hasn't been tracking consistently either. So it's a goner.
I researched it here and elsewhere and I found zero people that were unhappy after removing the first reg. So worst case scenario, in the odd event that the performance is negatively impacted from me removing the first reg, I'll just pop it back in if need be. But I doubt that will happen.