I cannot speak to the specific speakers, but I have made three jumps within the Sonus Faber line of roughly double or better the cost ($6K, $13K, $32K). Is is worth it? Holy cow, yes.
When established audio companies build product lines, they consider build costs and performance. They carefully weigh the performance against the competitors and within their own lines. Therefore it is a very safe bet expecting a big improvement when you double the price (my rule of thumb in audio... at a minimum double the price). The only thing to be a little cautious (I doubt this would be a problem), you can oversize the speakers for your space. Probably will sound better... just not as good as it could.