Switchable rounds are already in the game and they are neither unnecessary nor hindrance.
Currently M36 gets timed AP round that currently make little sense to use vs many targets. That probably qualifies more as an "unnecessary hindrance" since the player needs to know against what target and what veterancy each round is betted suited.
What side more effected is irrelevant as long as the game remains balanced.
The solution would simply make medium tank more attractive since they will not be shut down once "heavy" Tds are built. It will also create more room for medium for medium Tds like SU-76.
The infantry/TDs has imply gone for far too long.
The m36 hvap is intended for the heaviest armoured targets. The hvap pen however is indeed redicoulous. But so is twp on the pak40 wich also stuns the target. Its however not difficult or a hinderance since its a timed ability instead of a toggle. it will return to normal afterwards.
Unlike the sherman and isu, even being free i find them a hinderance. Not needing to switch is a better option. Wrong target shows up and you need to pull back to switch ammo. Same with td's if they get switchable rounds.
Hey thats a medium o shit a heavy as well, better switch to rounds with lower rof, but then the medium has become a bigger threat and i still need to move back even if i have multyple td's.
And since axis can field mediums and heavies more easely at the same time this effects allies more.
It puts more micro tax on the td,s. Allied stock mediums already have a higher micro tax. And then the td's will have it as well. So it defenitly matters who is affected more.
You will have axis heavies like the tiger dealing with tanks and inf no problem. Allies need a td loaded with rounds for both types of tanks. Tanks and inf to deal with inf.
Panthers deal with medium and heavies alike, and now probably gain a buff vs td's if the swith to heavy tank ammo with lower rof. P4 still works vs mediums and inf and also gets a buff if the td is in anti heavy mode.
In short this will give axis armour way to much buffs across the board. While only stock mediums from both sides need it. Unless both panthers and the jagdpanzer get the same switchable rounds as well.
As for the su76 it is bad because it comes go late for lv's and its okish only vs mediums, since it has to low pen and damage to be reliable esp vs okw. I dont see it getting more use. But i could be wrong ofcourse.
I think working on target sizes and acc so that mediums are hit less often esp at long range is a better way and causes less unintended concequences.