Nagra is PP, my preference actually. I actually am surprised you like AGs- they are different than the speakers you tend to enjoy.
Have no interest in the Mezzo, nor the +$20k budget. AG's main US dealer has told me before while they sound great, its not the best use of funds. The big step is from the Uno to the Duo because of integration, the removal of horn coloration, and better drivers. He actually believes its a bigger step than Duo to Trio.
If you compare AG to YG, the YG will have superior imaging, transparency, and detail. Honestly, its not close - that's what I mean. YG is like a lens has been removed from the sound. I'm sure
@bonzo75 would agree.