The only drawback I notice when playing with MOi3D is the viewport speed.
When I start filleting objects the frame rate drops badly. I do have a fast system and even with Cinema4D I do not have problems with the viewport speed but with Moi I do.
Is this a know issue?

I have a laptop with an I7-2720QM 3.30Ghz 16GB ram and a 1GB NVIDIA GeForce GT 550M GFX.
So that is not a bad configuration.
On my PC I have a Radeon 5770 GFX and it shows the same slow viewport speed.

Peace,
Rich_Art. ;-)