Based on rumors there are 2 patents that exist for this Lens's mark 2 version. and one of them is a Ring Style zoom rather than the push-pull design.

I rented this lens a while ago and optically there is nothing I can fault on this lens. My only issue was the Jerking off action of the Push-Pull design (using such a design for the first time)

I am waiting for the ring type zoom version of this lens but I can wait as I am in no hurry at all. I guess (my personal opinion) it would be worth putting an extra 200-300 dollars for the new design (If it comes out).