IME that is more the cab than the amp.
To a certain extent yes. I think Ron had some issues (Also very low tuning and massive SPL's) with tube power sections not being tight enough with such low tunings, which made him go to massive solid state power sections. I'm sure he can give more details. I'm by no means in his ballpark as for as tuning/SPL goes. I tune in BEAD, and play smallish venues.