I think I can hear a difference. 12" speakers sound fuller and better. It depends on the amp maybe. Some amps sound best with 10" speakers. Lany Lionheart & Fender Devile are two amps that were specifically designed with 4x10 speakers. I would think the same goes for cabs. I don't know but this is an interesting thread. I'm looking forward to learning something about this subject!
The knob galore amp - JVM is 4X10.