The biggest issue with most piston guns is the proprietary parts.MWS is awesome.
My only issue with it is losing the "plug and play" feature of being an AR.
Sure barrel changes/maintenance are as easy as can be as long as you have the proprietary MWS extension.
So you are limited to LMT barrels - which tend to be spendy - or scrapping a barrel and having one of the few smiths that do it fit your choice of barrel with the MWS extension.
My 16 inch CL shoots fine but I want to someday fit a premium barrel and it wont be an easy change such as I could do on my own with a DPMS pattern rifle.