If HTC is going to add in a light tank, then it needs to have more armor than the M8 and M18, be at least as fast as the T34/76 (34mph), and have a decent enough gun to fit above the M8. Case in point, it needs to have the speed to scout and evade and/or flank and attack. Otherwise it wont have much of a use.
The Stuart has the same gun as the M8, but more armor than both the M8 and M18 (which isnt saying much). What good would the Stuart be in AH?