"I have been considering buying Rhino to be a Companion to MoI!!!"
You hit on a sentiment that had come to me through frustration the previous day: I had to do, what I thought, simple vector tracing of some art work. I usually go to "Inkscape" for line work, as AI has very uncomfortable line tools and process - this is what ensued:

" Lets start with a throught-point curve" - oh yeh, don't have it.
"Control-point curve", nope.
"Dammit I have to muk-around with those damn handles again!".
"Now where is the 3 point arc and circle?", ???, "intersect/fillet/blend/rebuild, ???!!!, inferred snapping and dynamic guides, ?!!!!!!."
"Dammit this interface is making my eyes bleed!"
"Note to self: if you do line work go directly to MOI - any type of complex technical drawing(that requires 3d-line-views, go to MOI) - if you want to relax, MOI -- Use AI as its companion".

Warning: feature requests ahead :)
There is one nice feature I miss(from Inkscape), creation handles persist past the point of creation(eg. 3 point circles have the 3 points left adjustable). And line intersection and trimming could be streamlined by allowing the 'brushing' away of intermediate line segments. But relatively speaking, MOI is heaven.