I personally don't think that libgfxinit instead of vgabios or vice versa will make any difference in this case. I'd recommend to test native raminit vs mrc.bin instead.
Correct me if I'm wrong but isn't the mrc.bin Haswell specific ? From what I recall I never saw an option in "make menuconfig" to choose native raminit or mrc.bin on IvyBridge. If there is such an option (now) I'll definitely try it!
Sorry for a long reply too. About mrc.bin: no, it's actually possible to use mrc blob on Sandy/Ivy, but as I see it's not supported across all boards. X220 has support, other boards needs patching (or maybe patches are already on gerrit, I'm not sure). It shouldn't be hard to get it working, though.