Two things I would like to see in LR4:
1) Ability to choose 3 external editors. I have one set for CS6, and one for Topaz Fusion, which allows me access to my Topaz filters. (NIK, fortunately, installs itself as available as Edit In, but Topaz doesn't.) I also like to print from Qimage, and by choosing Qimage as an external editor I can send a softproofed version of a file to Qimage. However, I have to go into LR4 Preferences and change to 2nd external editor choice to do this.
2) When softproofing in CS5 or CS6, I frequently use the Color Balance adjustment layer, which gives me precise and repeatable adjustments in numeric form. The closest I can come to this when softproofing in LR4 is to use individual color curves (R, G, or B), which can produce the same effect. However, I wish their was a numerical readout along with this. (If I missed it, I'd appreciate being directed to it.)