It doesn't matter. You will visit both web sites every day. Regarding your MPX--is it a gen 1 or gen 2 ????????? Doc in Pa.
It's Gen2 MPX-C-9-KM-T. I only have two boxes through it, but no malfunctions so far. It's shooting way low so I have to adjust the front sight post - but I don't have the proper 4 prong tool yet Not sold on the stock sights yet. Will be getting either a tritium front post or a Self-Powered Day/Night Reflex Sight for it.
Only complaint: The collapsible stock is stuck in the extended position. Can't get it to release. Will be calling SIG this coming week.
As far as the stock is concerned...you have to get a flat head screwdriver or a flat piece of metal to pry up the bottom of the folding stock. It is very stiff. I have a gen 1. Outside of the stock crappy trigger, I love it. Doc in Pa.