Kinda hard to tell from the pictures, but did the locating pin come out or did it break/shear off? Was end gap checked when installed? Cylinder bore straight and true top to bottom? (from my experience, most cylinders are a bit hour glass shaped and tighter through the middle- if not all the way down, and need to be straightened out- even factory new cylinders). Were the ports properly chamferred so the ring doesn't snag?
MCB is using SPI pistons with Skidoo/Elko rings. Nothing special about them.
Wish Pro-X made Skidoo pistons besides the 670 slugs, those are some outstanding cast pistons in my experience.
I've had more negative experience with Wiseco forged pistons in 2-stroke nikasil applications than positive to trust them with the wide clearance needed.
Haven't run any of the cheaper Taiwan OEM type pistons in a while, used to run the heck out of them back in the 1990s though with overall good results. In fact one of our best running and longest lasting mini-sprint car engines went 2 seasons on a set of Kimpex el cheapo pistons in it.
Blanket statements about most any product in a 2-stroke snowmobile application is almost unrealistic. Sure it sucks when something fails, but you don't have that many options to chose from either. Just dropped a set of SPI dual ring slugs in my 2004 800HO Summit, will report how she holds up. Devil is in the details most often when rebuilding engines.
