I've just registered to the forum just to contact you-- I am sorry for the PM, I'd have preferred to reply within the thread but the forum for some odd reason, says I "cannot reply to this topic"!
Anyhow, I just want to clarify something. Have you tried running 4k @ 60Hz via Windows on late 2013 13'' rMBP with Iris? Was it successful? If not, do you think this can be possible in the future? (I've read conflicting Intel documents on Iris regarding 4k 60Hz capability, hence I've still got hope)
I did not try any version of Windows on the 13" rMBP (late 2013). It's not my own machine, just a machine at work which I was able to borrow for a couple of minutes for some quick testing, so I will not be able to do any Windows tests.
I don't know if Iris is capable of UHD/4K @60 Hz, but if it is, it probably does need drivers updated for MST support, much like AMD GPUs got in v10.9.2 and NVidia GPUs are about to get in v10.9.3.
I did try the NVIDIA web drivers when I was trying to get 60Hz working initially, but I'm 95% sure I wiped all traces of them from my system.
I'm using Chameleon v2.2svn r2377 right now. Maybe you'll find my plist configs useful.
Thank you Ricky, I moved your configs in place, set a serial number and will try in a bit (might have to remove P- and C-states too for my board).