I think schreck on sturmpios in the current state isn't good and feels awkward and here are the problems with it.
In combat you need to keep AT squads safe at long range so they won't get focused. Because of that AT weapons work well only on long ranged troops so they can stay at long range and do some damage vs infantry until a vehicle shows.
The first problem with schreck on sturmpios is that this squad is only good up close. So you either run up close, do some damage and get forced away or you stay at range and be useless vs infantry. You can say "What about pgrens and sappers?". The reason that AT upgrade works well on them is because they get 2 weapons as opposed to 1 and can be used as dedicated AT. You just don't send them vs infantry unless you have an edge in the engagement.
The second problem is that sturmpios is a 4 man squad so schreck cuts a lot of AI dps. So sturmpios are neither good vs AT because they have only 1 shreck or vs AI because the dps is too limited.
I see 2 solutions for this. The first is that sturmpios should be able to unequip schreck similar to the minesweeper. That way they can still be good vs infantry while keeping the ability to fend off a vehicle.
The second solution is give them 2 schrecks. This can work too though I don't like this too much because sturmpios would be a better version of AT pgrens.
Also cold immunity should be removed from the upgrade and its price should be reduced to 60-70.
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