Yes the Germans were very much aware by experience exactly the sort of devastation the Mod 97 trench shotgun could inflict whether assaulting a trench or protecting it firing 00 Buckshot made short work of the enemy at those combat ranges.
I think I read in one of my books that if you were captured with a shotgun then your chances of survival were very slim indeed similar to Hitler's infamous Commando Directive of WWII.
In the end the Garandproved to be the superior weapons platform and for the U.S is rightly regarded as a war winning rifle for their campaigns as the Lee Enfield did for the Commonwealth forces and their campaigns.