Hi Bob, the other thing that can give you a good feel for things are the MoI introductory video tutorials here:
http://moi3d.com/3.0/docs/tutorials.htm

Those go step by step on how to build a few different objects and highlight how the profile curve focused modeling strategy works.

As a comparison you could try constructing those same 3 objects in TinkerCAD and see how difficult it is - TinkerCAD is more about stacking together premade pieces and you aren't able to have the same feel like you are drawing something completely custom.

But if you don't need real curved surfaces, I would think that SketchUp would be something that you'd want to look into rather than TinkerCAD.

- Michael