Tech costs has nothing to do with MP drain from replacements when talking about army composition. Ostheers inablity to rely on a mainline infantry makes them into a house of cards faction... if you doing well you are doing really well but one good flank or lucky grenade/mortar can wreck your army so fast no other faction can compare.
Let me put it another way: I predict USF's early game will get downtuned a bit next patch. Adding cheaper Grenadier reinforcement on top of that would likely cause imbalance in favor of Ostheer.
Against Soviets the Grenadier bleed becomes quite apparent in the mid/late game, but that's rather because the 7 men upgrade makes Conscripts too efficient IMO (lower reinforcement on top of 30-35% more dps and already good veterancy). It's a seperate issue.
Just don't rely too much on Grenadiers and you should be fine, even this patch. Watch players like Jove as an example. He regularly gets 2 Panzergrenadiers to back up his Grenadier builds and makes excellent use of them.