Remember, the original question was about replacing a 4x10 with two 1x12. I still contend that the best way to do that and retain the 4x10 sound is to go for two 2x10s (it goes without saying that they should not be cheap and nasty, of course). It IS largely down to cone area (assuming material quality, construction, etc is equivalent). You need to move air for low frequencies and there's no escaping that. These mini rigs sound great in the shop, but put them in a large space, with drums, etc and they sound very anaemic. You may get mid and top, but there's no 'heft'. SpL measurements are of little use if they don't take account of frequency.