Shrecks are fine in my opinion, in the right situations they can be devastating. But they also have their weak points.
If I feel defensive I use Pak40s as AT. (needs fausts or mines for optimal performance)
If I feel offensive I use Shrecks as AT. (Needs other agressive units (Basic PGrens, G42 Grens and/or Pz4 for support).
Additionaly I think a change in tec and building cost should be made with the new patch. Increase the cost for the first Tec from 100MP to 200MP, because now it gives you Pgrens without the building and reduces the risk of a T1-T3 rush (You can use the shrecks to survive until your mediums hit the field). To balance things out reduce the cost of the T2 building from 200 MP to 100 MP, because it lost the Pgrens and I fear many will skip it if it costs 200MP.
Just my opinion.
I dunno, the whole point of moving pgrens to T0 is to make them more accesible, so they get used more often. They already cost a lot of MP, I don't think it's necessary to move 100mp from T2 to BP1, this would only serve to make the one pgren squad most players will probably consider to get less appealing(going for 2 or more squads is too much of an investment in most situations).
Also, most players get T2 for the light vehicles, and the PAK40 is typically preferred over pgren shrecks, I doubt saving 200MP and 20FU would make players consider skipping T2 and relying on pgrens instead of getting the PAK40. It could help players that already do that, but then they are already doing it fairly succesfully(unless they like to lose), so they have some other strategy to compensate for the lack of T2.
Pgren shrecks aren't really better than a pak for AT, they have their pros and cons over it, but aren't directly better, typically harder to use and keep on the field, and cost additional 100 munies, which could be spent on mines/upgrades for grens.