I am not familiar with your particular Sony speakers, so I cannot comment on your specific comparison. But, I recently upgraded from Cerwin Vegas (front), Phoenix Gold (side/rear surrounds in-wall), and Def Tech MK100 (back surrounds), and a Klipsch Center Channel.
I went with Mythos Ones all around on a 7.1 system, with a Mythos Eight for center, and for the time being I am still using a Klipsch KSW12 for a subwoofer.
I noticed an amazing improvement in sound quality. Amazing clarity, especially when listening to dialogue from the Center Channel. The Klipsch center channel was a good speaker, but there were times, when watching a movie, that dialogue just could not be understood, and I would have to rewind and listen again, and sometimes still couldn't understand the dialogue. I would have to turn CC on, which I don't like to do.
With the Mythos Ones, and Eight for a center, I have eliminated the, albeit rare, muffled dialogue problem.
I know that my words are subjective, but the Mythos Ones produce beautiful, crisp, clear sound.
The 120" picture produced via my 1080p projector is better than the commercial cinema's picture. And now my sound system, with my Onkyo 876 and M1s and M8, blows the commercial cinema's sound system away, IMO, especially considering I am not listening to someone sitting behind me, crunching popcorn in my ear. I really have no desire to go to the commercial movie theater anymore.
I think you will be very happy! Do you have a sub yet? You will need a sub woofer with the Mythos Ones. The subwoofer makes a big difference, as opposed to the Mythos Ones w/o a sub.
Give us an update when you get all set up.