The 1820 and 3620 Peaveys make a lot of boomy humpy mid-bass with very little wattage required to get that loud and present. They also don't make much lower bass and run out of excursion fairly easy when you present them with a signal that has more true LF content.
I used to have an 1820 and a lot of power available to it. It was a good solution during that period. Now? A 15/6 fEarful just clobbers it at every frequency and won't blow Tens or crossovers or fart when pushed. And I won't either, when I'm bending over to pick it up.
I think you may be missing the point here. You're discussing speaker cabs from a "sound" point of view. An analogy might be, "which looks more impressive and imposing, a battleship or a nuke sub?" A battleship of course. Which one is actually more effective though?.....
Efficiency and weight issues aside, those old Peavey cabs do have a particular voicing which has an appeal to some.





