I've added this tank to my game as a 12/6/1 unit. The weak defense and slow movement forces it to travel with infantry, just like it did in WW1. The movement also forces it to coincide with, not replace , cavalry units, which remain the only quick way to hunt down injured units or rush units to an unlinked front.
Since I'm not a fan of the DYP "more is better" school of thought, I rarely add units, but this one really adds something to the game. There would, otherwise, be this monstrously huge hole between Cavalry and Shermans where defense has an almost insurmountable advantage that makes the game crawl to a halt in the industrial age. This unit is just what the game needs to get you past that period.
A definite must have.