Vienna Acoustics Mozart Grand v Focal 826V

I suspect the 826W would best both. 

Yes. Completely different speakers. You want one you can feel the music more, it's flow, it's groove and emotion, to me that is the Vienna. You want one you can hear a better portion of micro dynamics and more details to the sounds, the recording space, to me that would be the Focal. Both very good speakers and so could fit what you want with what you have. Best advice, you should listen to them. 

I have Vandersteen 2C (late 80s) and Infinity RS 2.5 right now.  I prefer the doped tweeter in the 2C to the late metal tweeter.  I assume the above speakers are in a different league?

yes, different league

very different