I have a closed back diagonal 2x12 and 4x12. Its not with rectifer tones, but with classic tones.
You can get the tone in your head a lot cheaper with the diagonal 2x12. Part of the quest for tone is finding out what speakers you love the most and which one's mike up the best for what you're hearing. a 4x12 is a lot of speakers to buy and try.
The 2x12 diagonal sounds like a 4x12 but is smaller, lighter, better sound dispersion on stage, and a 4x12 gives more apparent loudness - meaning you get more power tube action with a 2x12. I can run my amp on stage in the sweet spot with a 2x12 with 40W tubes (EL34's). I have to drop to 20W (6v6's) with the 4x12 and run the amp below the sweet spot. Some of that is speaker sensitivity, too, but my speakers are not 3dB differences, so I'd say 50% of the difference is # of speakers, and the other 50% is speaker sensitivity.