I've done a few logo inports for clients, and the AI importer ONLY works in the spline modeler. If you need to, convert to vertex after importing, for UV mapping, sub-division, etc. I also found that depending on how many points are in the .ai the importer may take awhile to finish creating the model. If they placed 200 ponts on the curves then C has to recognize each, convert it to the points on the cross-section, then extend to the next point on the extrusion line. Good luck!