From Sonus Faber Extrema to...

I would imagine you have had them for quite a while and have brought you many years of joy.  If that's the case, to avoid the regret of selling them off, I would explore other speakers by making those purchases one at a time while keeping the Extrema's on standby just in case I couldn't find anything else I liked better.

I'm in a similar scenario with my Vienna Acoustics speakers.  I have looked around at other offerings, but I just love the way they sound and look so I don't think I could sell them before finding something "better," only possibly after.

Yes it would be the best case scenario, but it needs an amount of liquidity that I don't want to throw in. Furthermore, I'm quite sure I can sell my Extrema in a blink, not so sure about any other expensive speaker I could think about.

Beautiful system.  The speakers you proposed are all nice but very different in presentation from the Sonus Fabers.  What is your possibilities to travel to some high end stores that display a model you are curious about or attend an audio show to experience many options.  Certainly either option will not give you exactly how they will sound in your home, but also it can rule out some aspects of the presentation you do not think will work for you.  

https://speakerchoices.com/index.html

It depends on what you think you are missing.  I own a pair of Vienna Acoustics Liszt speakers which I really like, but are always on the lookout for others.  I previously owned the Avalon Ascendents and the Liszt surpassed them, especially in the bass.  The Avalon customer service is bad.  I recently listened the the Wilson Audio new Sabrina.  My complaint with Wilson has been the upper end treble.  These are better but not to my taste.  I prefered the Liszt to the older version of the B&W 803's.  I use a tube pre amp and solid state mono block amps.  (Herron Audio).  Just my two cents.