It would be better to allow an additional Panzershrek to be purchased when OKW built a T3 building rather than giving the STP an elite Panzershrek
Panzershrek with mine sweeper? No
Make STP get additional panzershrek to 50muni
Well that's surely an option. I'd prefer one of zhe other solutions though due to the fact that they should be easier to implement and the fact that Sturmpioniere would thereby become better Schreck PGrens (slightly lower AI, but building and repair capabilities plus other utility)