My take - Limited conceptual capabilities due to exclusive Nurbs choice.

 From:  PININ
63.3 In reply to 63.2 
"I agree, it would be cool if MoI had the same capabilities as a $20,000 app. I hope you realize that this is an amazingly high expectation."

I was lamenting that the module was only inside a $20000 application. The whole application have many more modules capabilities to probably justify the price tag.

"Let me propose that there can be other definitions of "conceptual modeling" that involve doing quick rough sketches of a model, not focusing on reflection lines or detailed surface styling."

Yes of course, but i disagree that is a desirable path if one wants to appeal for conceptual work from Mechanical Design to Product Design.
One of the most important issues of the Conceptual work is the time spent. If i can cut that time i can make many more iterations. Nurbs is generaly more complex to start modeling except if i have to model just a couple of big surfaces, and it is also it is more dificulty to change afterwards . I am far from happy with Subdivisions by the motives i stated in first post and i agree that a mix Subdivision+Nurbs approach is desirable, that was the reason i posted that link.

"The bottom viewport buttons are set to do a rather smoother motion which may not be to your liking, the right-click-inside-a-viewport method is probably closer to what you are used to."

You're right, i started to use RMB in last test. It's a little slower than XSI but the diference isnt such that i would call it a limitation anymore.