Have two 20x versions, and have no trouble using them. One lives on an Anschutz sporter. Works fine at range, and vs barn pigeons and red squirrels.
There's a downside to a tolerant eyebox - increased potential for parallax error. Consistent mount and cheek weld are good habits to develop. Not just with shotguns.
You're definitely right about that, and I appreciate the advice. I was contemplating how to balance those two things. The first is to get a scope with parallax adjustment, second is to shoot only at distances within your scope's parallax setting, third is to use a scope with a smaller objective.
The non side focus scopes I have all have parallax set to 150yds, which is near my maximum hunting distance. I also plan to use a 40mm objective at largest going forward.