If you are playing larger venues, and you are used to two 4x10s, I would hesitate to recommend a 2x12. A good high end 2x12 can cover a 4x10 and more, but not much more. It depends which 2x12 we are talking about.
If I were in your position, and I wanted better portability, but enough speakers to push the sound, I'd opt for two 8 ohm Aguilar DB212s. I've had two, returned to just one. They are, IMO, stunning.
If you want really light weight, what about a Bergantino CN212? High end, and expensive, but they are very highly regarded even though they are only just getting out the orders for them.
What about a 6x10?