There are a good portion of guys here loading two speakers diagonally in 4x12s and essentially making them oversized 2x12s. That has got to be light. (Edit: i just noticed @311boogieman already brought this up)
I have had four cabs I think. I never weighed them, but they are all light. The mills is a lot bigger so i have trouble walking it through a doorway between my size and its on robustness. However i would guess this is lightest to heaviest
1 randall xl
2 jcm 900 cab
3 evh stealth cab
4 mills afterburner