Hi ..

I use both programs and prefer MoI for modeling. It is slimmer and more intuitive than Rhino and the visual graphics are sharper and easier to work with than the options offered by Rhino.
That said, Rhino is good for drafting. I do architectural work and need good dimensions and text as well as visible differences in line weight and type (which MoI does not offer yet) and I use plug-in rendering tools in Rhino which MoI does not offer yet. Though MoI will export files easily that can be used with many rendering programs. I just happen to have purchased ones that run within Rhino before discovering MoI. Rhino also offers a 3d pdf plug-in from SimLabs that I use often ... Though MoI will export a file completely readable by the SimLabs 3d pdf software.
MoI offers better meshing than Rhino.

From my perspective MoI is a much faster modeler than Rhino and I would not want to live without it. I look forward to further development that will include some drafting and dimensioning tools.

In the meantime, Rhino is my favorite drafting tool (though I used AutoCad for many years) and I would not want to do without it though I have a number of other, good and low priced drafting tools that prepare excellent .dwg files.

Depending on what you actually do a great combo is MoI for modeling and Draftsight (free) for 2d drafting and dimensioning. Add the low cost SimLab Composer for rendering and 3d pdf files and for less than $500 you have a master tool kit.

good luck,
eric