So I did a little looking again. Pretty much everything you said is real.Parts wear/breakage, Sig being Sig with constant new generations while stopping support of older ones, need for very regular and thorough cleaning, I heard the word "finicky" a lot but can't tell you what that means exactly.
They all loved them for the first 15-20k rounds and couldn't keep their panties dry talking about them. Then they got quieter. Then they got new guns.
They are soft no doubt, I was pretty amazed the first time I shot one.
Looking at PCC Nats equipment survey, MPX's are not dominating. They are less than half as popular as JP's, which are not half as common as home builds.
Problem is now after looking at a JP.... I want one of those. Thanks a lot.