Suggested MAJOR Improvements:

1. Improved Fillet - In my experience, it often takes a couple dozen seconds to produce the same results that 123d Design, FreeCAD, Fusion 360, ViaCAD, and others generate virtually instantly.

2. Surface Matching - http://docs.mcneel.com/rhino/5/help/en-us/commands/matchsrf.htm

3. Surface Rebuilding - http://docs.mcneel.com/rhino/5/help/en-us/commands/rebuild.htm

Features 2 and 3 would be particularly useful for patch modeling workflows, and with the above three developments, I would no longer have a need to use other CAD software.

Suggested MINOR Improvements:

1. Customizable Viewport Navigation - I prefer MMB rotation, Alt + MMB panning, and Ctrl + MMB zooming. Currently, I use AutoHotkey to get this behavior, but it would be better if the option to do so were built into MoI.

2. Pick Viewport Center - I would like to be able to press a button to set the viewport's center to a point directly under the mouse cursor and on an object. Perhaps, this is possible with scripting, but I'm not aware of any ray cast functions.

3. Zoom to Center - The option to zoom to the center of the viewport would be greatly appreciated by people like me who dislike zooming to the mouse cursor. Currently, this is only possible by using the zoom button.

4. Z-Axis Viewport Rotation Inversion - Currently, if you rotate the view by dragging the mouse from left to right, the scene rotates counterclockwise as seen from above. This means that the scene rotates in the opposite direction as expected when viewing from the bottom. One solution would be to automatically invert this behavior to rotate the scene counterclockwise as seen from below once the view passes a certain threshold. If this explanation doesn't make sense, I am proposing that the viewport rotation be handled like Blender or Maya instead of the current way that is like Modo.

5. Lit Sphere/Matcap Shading - This is achieved by mapping the x and y components of camera space normal vectors to a square image of a shaded sphere. The mapping is offset such that the normal vectors (0, 0, 1) and (0, 0, -1) correspond to the center of the image texture. Not only would this enable massive libraries of lit spheres to be used in MoI but also it would provide a "poor man's" zebra stripe shader for surface continuity analysis (http://cadjunkie.com/9180/matcaps-in-modo-zebra-stripes).

I hope that my suggestions don't portray MoI as inadequate. It is a fantastic product and an absolute pleasure to work with.