Wilson Sophia III vs Sasha

Your mind seems made up. I think in this case your not going to be happy after your purchase of the Sashas for a long time and many many upgrades!!! Why not enjoy and upgrade your current system with the Sashas in mind??? I'd start with the transport, then ASC 16" tube traps in the corners. I tried GIK 244 and the ASC worked a lot better for me. I think you'll find getting a tighter well defined bass and cleaner mids without bass smear will let you hear how good the Sophia lll is.
Many people saying very similar things here, I would listen especially concerning treatments!!! People like Jfrech and his vast experience with Wilson products this is knowledge not a guesstimate!!!!

Short simple and great advice:

12-11-11: Onhwy61
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?

Best of luck in your quest. Please keep posting your experiences.