I know you will still get playable frame rates but there are games as you pointed out that prefer the high IPC of the intel cpu's and do show a difference SC2 was just one example there are some others also.This was true 3 years ago Lionvibez. Back then an OC'ed i5 750 came in at mid 50's in Starcraft 2 while a Phenom 2 x4 965 clocked in at a still playable 40 fps. However now the Piledriver and Vishera core AMD's are quite a bit faster than the old Phenom 2's.
These new AMD CPU's still cant get to the framerate of the Intel CPU's in CPU dependant games (which are getting fewer all the time) but we no longer see a scenario where having an AMD processor will actually cause an obvious loss in playability.
And I do not think Pile driver @ 5ghz will be greater than a 2600K @ 4.5Ghz but we will have to wait until its out to confirm this. And once you go up to Ivy or Haswell the distance should be greater.