Well, the mk2:s. They are now under repeat play for the days. They have a grand total of 20 hrs of play time now on them. My S3:s had approx. 700 hours when they left.
So, straight out of cardboard boxes (which, at least for my set, were in quite a state and one of the grilles was bent, but that´s another story), I´d say they are quite an evolution. If that translates ito revolution, that remains to be seen and heard.
The tweeter is a definite improvement over the mk 1:s. So is the overall balance and neutrality, even now. There is more bass, but I guess the bass is going to improve most.
Even now, it is a better speaker, more coherent and lifelike, I can´t wait to hear it even 70% broken-in.
Expensive? Yes, for my money it is. Guess I just don´t have enough money

Worth it over the mk 1?? For me, definitely. YMMV, tho.