Last night I faced a shock spammer. I saved the replay and this guy literally on his build order did not make any infantry but maxim and shocks, lol. I screwed up bad in the early game, so I was at a disadvantage for that. This guy had at most 3 shocks to make assaults. The maxims weren't brought along, it was just 3 shock blob. I stupidly took waaaay too long to get an mg, but an mg is needed. Grens get wiped scary fast. It felt very similar to fighting the first Sturmpio squad with cons. Even retreating, they die on retreat. I'm just talking about 1 on 1, not the 3 shock blob all shooting 1 gren. It sucks to lose the vet I had, but I can accept them losing. What really left a bad taste was pgrens vs shocks. Pgrens get eaten alive and they are just a little less in cost from the shocks.
I don't think anything should be done to the shocks, in my case I could have done better with an ostwind to deal with the blob, but I do think pgrens need a little more durability. Pgrens should likely still lose 1:1 but it should not be so overwhelming unless their cost and pop are reduced.
The good thing about shocks is that their path is predictable. They NEED to go as close as possible to your units. If you see shock spam, always mine the opposite site of your cover and wait for them. Pioneers mine field are also amazing to stop shocks incursions.
Also, any light/medium AI vehicle is just overkill for them. Usually you don't follow shocks with maxims or ZiS behind. They're assault and harassing units, so even a useless flameHT can send them to their base with their tails between their legs.
Ostwind or a Luch are just ultra-hard-counter for them.
And finally, a drawback that shocks have is that they can't kill retreating units as effectively as gren/lmg, obers or any other long-range unit. Unless you let them engulf your troops by them you could always have a safe retreat.