You're right I did get a little off topic. At the same time, you seem to contradict yourself when talking about call-ins vs the innate advantage of heavies over mediums. I mean you can't say that t34/85s are on par with the heavies and then say there's an imbalance. AND I still think you can't consider units in a vacuum. I mean why try to stack up plain t34/85s to heavies when you know that you're going to be using Mark Target? Same goes with USF and p47s. Unless you think that the balance is just so screwed up, then it seems like a moot point.
Also I agree with the Ciez thread about call-ins themselves being too strong, regardless of the unit type. However I don't think that should affect this discussion.
Because there are other doctrines besides Guard Motor ? You can call in individual or double 85s without mark vehicle. Also why are you focusing on other abilities? If we consider mark vehicle, P47 and etc we can start considering AT strafe (Lighting), pak40 (TWP), better snare (faust, native with higher pen n range), better infantry AT, etc.
I guess i'm going to put it more clear.
Call ins > Stock tanks: performance and price effectiveness
Heavies > medium: ease of use and micro requirement for results achieved.
Because people already hate the Kubelwagen and the Puma, could you imagine the rage if they also effortlessly outran anything that even had a chance to kill them? The slowest vehicle in the game is 3.0 for the upgraded Jagdtiger, and the fastest is 7.3 for the M3 Scout Car and Opel Blitz. Infantry move at 3.0 and Medium Tanks are 6.0 - 6.5, only twice as fast as jogging. Heavy Tanks speeds are 3.8 (KT), 4.7 (Tiger), and 5.0 (IS-2).
Plus, the vehicle movement patterns don't change based on speed, so an M3 taking a corner looks fine, on overdrive it looks a bit unsteady, on overdrive and on a road it looks like it's breaking the laws of physics. Increase the overall speed and it'd look like it was the Planet Express ship moving the Earth around itself rather than actually driving.
Maybe i should have said it, why not make heavies slower either on max speed or acceleration. I wouldn't touch speed of light vehicles.