I can joke and say I want T-splines for MoI?
T-splines for rhino are so buggy (v2.0) when you work in symettry and delete a face it hang'n'crash.
And when you start to have a complex model (like a coca cola bottle) it gets very slow even on a quad with 8gb of ram.
Also I think that Rhino is much slower than MoI (loading the exact same 3dm and moving the camera around, MoI is faster)