The regular MCU is the original (successor to the HUI), the Pro is the new version. We used the HUI at my first studio, and the regular MCU at the second studio I worked at. The MCU is killer and I have wanted to get one for a long time since working there. I haven't had a good enough reason to get one just yet though, so I'm just patiently waiting until I get to that point, hehe.
~e.a