Chinese Democracy would probably sound more dated. At least the current band connects more the sound that's popular in nowadays rock (with a more electronic sound, keyboards etc.).
I personally don't mind Ashba's contribution for now. The things he does for Guns are great, I think (his solos, his versions of old songs), so for now I'm ok with him. The things he does in other projects are irrelevant to judge his contributions to Guns, IMO.
But then again, it's allways impossible to say what would've happened. Would Axl ever have reached the state in which he wrote these songs if Slash was there? Maybe, but not certain or even very likely. But I don't think there's a doubt that it would've been ace
! The combination Axl - Slash allways stood for quality (yeah, offcourse there were exceptions, but their amount was insignificant to the other results)