An MPX sounds ideal for what I want, but $1500+ for the gun alone is more than I can justify, especially with the stories you've told about SIG's attitude about customer service/warranty issues. I do load my own 9mm as it is, so developing a light load that still makes 130+ PF out of a 16" barrel would definitely be part of the plan for any PCC, but especially a blowback gun.
No disagreement there; the purpose of a PCC for us would be competition and fun.Even leaving aside the ballistic advantage of rifle cartridges, I would take 5.56 or .300 BLK over a semi-auto 9mm carbine every day for defense, based purely on reliability.