Yes, I think you will.
Firstly, you took an infantry unit and made it an armor unit. Look at the ratings for that unit now, the ones on the right, inf, arty and armor. Most likely you will notice that the armor rating still is pretty low compared to a unit that started out as armor. Don't lead the attack with this unit. You won't fare too well.
Also, tanks can get wasted by one shot from the enemy. Also not good. IIRC, anytime the AI sees something like this, it tends to make it a priority target for AP rounds, also not good. Enemy planes love them too.
As a good rule of thumb, keep units the same class when upgrading. Otherwise you take an experience hit that makes the unit less effective.
But on the bright side, you are not likely to get cut down by MG fire.
The A0 as a Transformer-type machine? Never thought about that. I usually leave the A0 as is, unless there's an upgrade for the HQ unit itself. The B0 unit is the command vehicle, which eventually gets upgraded to an APC or AFV.
I always catch a lot of grief whenever I let on about this, so I guess I am signing up for more. I usually play German and usually have a fairly large force and I always upgrade my A0 to the best tank I can get. I also totally fudge the armor rating in the editor because I figure that an upstanding Colonel like myself would have received a trained panzer crew from the rear.
People here always chastise me for it. "Well, I would simply knock it out and where would you be w/o your A0?" "It makes him a target." "You lose some arty contact." etc. etc.
My angle is that the German army always stressed leadership from the front and I am merely trying to simulate that. I commander of a formation SP sized would be up close, especially in advance scenarios. Let me give two f'rinstances: 1) Rommel led his division from the front (in a tank) during 1940; 2) Hyazinth von Strachwitz led his division from the front in the East (in a tank.) Both were Major Generals at the time.
The benefits were many. Morale effect for sure. The other is command and control. Commander with "eyes on" can much more quickly adapt than a CO hanging back near the arty park. Guderian said panzer generals must always be at the front.
SP models some of this. The rally radius tries to simulate this by having another rally chance, but only for a few units, given the scale of the hexes. In reality, the morale effect of having your commander shot at along with you is tremendous, especially from battle to battle. This is why Patton did it. SP cannot model this effect. Also, because you (the player) can see every unit any one of your units has LOS on, the command and control aspect of leadership is greatly distorted. Normally, you (the A0) would have to receive reports and keep the changing battle situation on a map and in your head.
This is not a complaint. I love SP the way it is. I just like the thought of doing things a little more historically, whether the game engine rewards me or not.
The only time I changed my A0 unit to a tank, was in Heros of the Motherland. Otherwise it never really made much sense. Infantry units would be OK. Since you usually want your A0 out of the line of fire, a tank upgrade is often an expense that has little return.
If you find yourself in a fair fight, you didn't plan your mission properly.