I have heard these. I can compare them to my Triangle Magellan Cellos. The short point is this: they are way better than the Cellos. Compared with Canton K3 they are similar, but I would say the Cantons are better. There is not much between them so if you prefer the looks of the Sopras that would, IMHO, be enough to sway me. Personally I prefer the look of the Cantons so, for me at least, it is a no-brainer to go for the Cantons.
More to the point is that I have had a decent audition with the Magico A3s. Admittedly this is a different presentation from the ported Triangle - Focal - Canton style. I had the opportunity to upgrade to the Sopras: I dangled and lost that opportunity. But now it is the A3 or nothing.
I auditioned them and found them to be very bright for my tastes and lacking in mid and low bass. The No.3’s were much better (although still too bright for me) even for the additional cost but are quite large. I would definitely audition the Magico A3s.