I had a Gen 3 and sold it after 6 months. I just couldn't adjust to the grip, and my index finger would never address the trigger properly, and I had all sorta problems engaging the trigger safety.
My son just purchased a Gen 4 and it handles and shoots like a dream.
Gunsmiths like all of us have opinions. It is a rather strange opinion IMHO. Maybe he has logic behind it. What is that? Did you really leave without asking?
I hope this logic does not carry over to his gunsmithing!