Hi Bard - most likely the ones that you are generating in Illustrator are actually generating polygon mesh objects.

That's a kind of object that is made up of a bunch of little triangle facets, and it's not so sensitive to things like triangles bunching up or overlapping on top of each other in tight corner areas.

NURBS construction techniques on the other hand are much more focused on a type of accurate solid definition, so things that might make messy corner areas or geometry that folds back over on top of itself is not as good of a fit for NURBS construction as it is with polygon mesh geometry.

Just overall NURBS modeling is kind of more oriented towards making stuff that can be physically constructed and not necessarily only used for rendering.

Unfortunately text characters tend to have a lot of things that are difficult to fillet, like sharp corners with compressed areas in them. Also a lot of fonts have been designed only with 2D output in mind and can have kind of messy geometry in them when you try to take the same font data and use it in 3D. Sometimes creating the text as curve objects and then running the Rebuild command on it and then extruding the rebuilt curves can help, since that can simplify a curve combining many curve segments into longer single segments:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild


But yes in general it's a kind of difficult area to handle, and techniques that polygon modelers might use may not be as good of a fit for MOI since the polygon modelers are able to get away with messy internal geometry that doesn't show up when used only for rendering instead of actual model construction.

Do you have one particular bevel that you're trying to do that you are having difficulty with?

If you could post the model file for it, I could try to give you some additional tips for that case. If it's got a whole lot of little face fragments in it, creating curves and doing Rebuild on it may be able to help quite a bit with filleting though.

- Michael