I'd like to see a T-34 also, but only because it would make for more interesting scenarios instead of having PzIVs on both sides. It would NOT, I say again would NOT, dominate the PzIVH.
Simply put, the 7.5cm KwK L48 on the PzIVH could penetrate the T-34's armor at all battlefield ranges. That was why the Germans introduced that gun, after all. The T-34's armor was only impenetrable in the mid-41 to early-42 period, when most German tanks had 3.7cm, 5cm L42, or 7.5cm L24. Basically, due to the total ass-kicking the Russians got in 1941, even though they managed to just barely stop the Germans in the end, they concentrated on production pure and simple. They were losing so many troops that the need for replacements meant quantity, not quality. The only design changes allowed were those that increased production efficiency, not combat power. So Russian tank design stood still for the 1st 1/2 of the war on the Eastern Front. Meanwhile, the Germans saw they had a problem and made changes to deal with it.
On the offensive side of things, the T-34/76's gun could penetrate the PzIVH, but not at will like it could vs. the 1941-vintage models of the PzIV. The 85mm gun that came out later, however, had no problem. So if AH gets a T-34/76, it won't be able to kill the PzIVH as far away as the PzIVH can kill it, while if AH gets a T-34/85, they can both kill each other at any battlefield range. So basically, it's a wash at best on this.
However, there are other factors to consider. The Russians viewed their tanks primarily as infantry support or for shooting up soft targets in the enemy rear after penetrating the lines. So normally they carried 2 HE rounds per AP round. Thus, even if HTC provides varying ratios like it does for the PzIVH, I'd still expect the PzIVH to carry more AP than the T-34 could even at its max setting.
Finally, don't forget the T-34/76 only had a 2-man turret. Because of this, the tank commander was also the gunner. And he had a big hatch that opened forward and stood vertically, so he couldn't see ahead very well from the unbuttoned position. Thus, if it was up to me, I'd model the T-34/76 in AH without any turret hatch postion, or at best totally block off the forward view therefrom with a solid hatch cover. Either way, it would be much harder, if not impossible, for a player in a T-34/76 to spot an nme from the turret hatch and then drop down to the gun to shoot at it.
So basically, the only unambiguous advantage any type of T-34 would have over the PzIVH would be higher speed. However, apparently the T-34 was MUCH noisier than other tanks, due to the design of its tracks. So other players should hear it from a greater distance than they can a PzIVH.