I use Moi for concept work, its got some clever workflow that makes it a joy to use. Its also a lighter/smaller program to use on a laptop with limited resources.

You can copy and paste models between Rhino and Moi which is very useful.

I find Moi does a better job of converting Nurbs to mesh.

If I cannot get a command to work in Rhino, I then try the model in Moi.

Rhino is very good, I use it all the time for CNC . Rhinocam and Madcam.