By buffing the Greyhound's base damage but reducing the RNG factor of its main ability you make the unit more desirable, and less rage-inducing to fight against. There is no reason that it can't act as a 3 CP doctrinal alternative variant to the Stuart for those occasions where you may choose to forego the Captain tier. Often doctrinal units are designed to fill holes in your standard tech tree, so why not?
That's the problem with doing those changes to the Greyhound. If you skip the captain tier, M20 is a better light vehicle choice in every situation. It has a consistent firing platform against infantry, way cheaper on the fuel, it has greater survivability due to smoke, the crew comes with a bazooka, and it lays down amazing AT mines. The Greyhound has better shock value against infantry, but I've used the unit more than most, and I've had it used against me. The whole "it squad wipes all the time" logic is a lie. It doesn't wipe squads any more than a 120mm mortar or a rifle grenade used against a bunched up squad hiding behind a little cart. Or a shock trooper grenade that lines up perfectly with a squad moving across a road.
Yeah, trust me. It's annoying losing an entire squad to the Greyhound. It's the same level of annoyance as losing that squad to any other explosive at any point during a match. If Relic nerfs canister shot, I better see nerfs to every single RNG based ability in the game. Again, if the Greyhound's primary ability is nerfed, you will not see it in-game anymore.
I mean, if that's what you guys want, have at it. We can make room for the M8 in between the SU-76 and Wehr puma.