At some point the head you are using wil affect the result. I have two Markbass 804, 4x8" for 800 watts 8 ohm, I was on the limit side when powering one cab only with an F500, pub gig with a rock band. Then I switched to the SD1200 and that cab turned out to be a little beast, now I do rock gigs with master at 9 o'clock with a single cab. So, the 4x8" is obviously less efficient than a 4x10" but with 800 watt power handling at 8 ohm, if you give it the right amount of power it'll compete with larger cabs easily. I think it's the same with single "super" 12 cabs, give them the right power and you can compete. If you are comparing a 4 ohm 4x10" powered with a 500 watt head you'll never reach same results with the same head and a single 8 ohm 12" cab, even the best 12" cab on the planet. All IMO obviously.