I see nothing wrong with the Die Step system... its actually one of my favorite things about Earthdawn and if it wasn't for this unique system (it was definitely unique at the time IMO) I probably would have never gotten into the game and I think the system was way ahead of its time. If ever there was a time to really showcase the Die Step system its now after the decade of d20 glut we were on the receiving end.
I really feel that people want something new now.
My idea... Drop the 4th edition part, and just call this Earthdawn.
Treat it like its a brand new game, and make it shiny.
Even if the system got changed... whatever system the designers go with MUST showcase the magic of the setting. That's always been the one thing about Earthdawn that has kept it separated from the rest. Keep Legend Points, Keep how the game uses Legend Points in buying them to increase in both Circles within Disciplines as well as tying Threads of magic items to characters. That must be kept.
IMO, you can change the core dice system to any kind of system, but if this aspect of Earthdawn was taken out of the game, how Legend Points work and how they are used to increase in power, than that is not Earthdawn.