I have a new to me 2017 Massimo MSU500 (760 miles 103hrs). Its been great so far and its exactly what I wanted.
I am and have been doing some minor customizations:
Line Xed the bed, Light bar with dash switch, 2" lift, Hunting graphics, 1.5" tire spacers, rear window and these items to be done soon - Rear Bumper, Quiet Muffler, Clutch Slugs, may put 10" rim on front like is on back and some sort of cargo bags.
My only real complaint is mechanically it could use a bit more torque on low end and aftermarket parts are limited.