The TS4 sole will be very slightly wider than the MMB and have more front to back radius. The MMB-17 sole, for some, could dig a little if they had a steeper attack angle and the turf was on the soft side. I do not expect that will be the case with the TS4’s.
Still a ways away on the TS4’s. Just received my second modification on the #6 iron CAD and it looks good, but still needs a minor tweak. I would not expect the TS4’s to be available until 2023. Could be late this year, but highly doubtful.