Your system is well balanced as it is. The recommendations for acoustic treatments are excellent, by far the best sound improvement per dollar investment you can make. As far as changing speaker go, the real question isn't whether you would spend an incremental $15k, but whether you're prepared to spend an incremental $40k plus upgrading source, cables and amplification? If you just can't live without the Sashas and money is not a big concern, then go for it. If you have to save up for the purchase(s), then most likely Wilson will have introduced a new upgraded version or model and moved the performance bar even higher and pricier and would you be happy with the Sashas then?
I would also be concerned that if the Sophias aren't disappearing after the dealer set them up in your room that the Sashas won't disappear either in that room.
I would also be concerned that if the Sophias aren't disappearing after the dealer set them up in your room that the Sashas won't disappear either in that room.