Thanks for the link!
If you head over to their GPU page, they make direct comparisons to the 2012 rMBP's graphics card as well as the other likely GPU candidates for Haswell rMBP.
Image
Let the iGPU vs dGPU flame wars begin (again)
This is exactly the reason I can only imagine the next rMBP with a dGPU. Apple can be "crazy, risky", but this is to much. For such an expensive (flagship) product, you can't go Iris Pro only. iGPU's are getting better and better, but it's not strong enough yet to completely replace dGPU's. I'm pretty sure it will be something like HD4400 + NVIDIA 750M.