I think IB is still going to be LG1155. You'll need a new SB-E cpu (ie 3960, 3930, 3820) for the R4E beast. Sources say the 3820 should be under $300 and hopefully the R4E stays under $400
I'm not sure I like where they went with the heatsink designs. I'm sure they have a purpose but they are not nearly as good looking as the MIVE or the RIIIE.