I have never had any issues with either 7.5 or 2011 unless it was an error with the model according to the Modset tutorial.
Please upload a XSI scene with issues for both 7.5 (.exp) and / or 2011 (.scn) so I can see if I can recreate the problem.
Im runnin Vista 64 bit Ultimatum
I have experimented a lot with the export setting and wrote a script where I just press a button and it converts to mesh and puts mesh and textures to my mod of choice.
SetValue "dotXSIExportOptions.project_name", ActiveProject.Name
SetValue "dotXSIExportOptions.output_file_format", 1
SetValue "dotXSIExportOptions.output_file_format_version", 360
SetValue "dotXSIExportOptions.sceneroot", True
SetValue "dotXSIExportOptions.polymesh", True
SetValue "dotXSIExportOptions.user_normals", True
SetValue "dotXSIExportOptions.tesselation", 0
SetValue "dotXSIExportOptions.nrbssrf", False
SetValue "dotXSIExportOptions.nrbscrv", False
SetValue "dotXSIExportOptions.animall", False
SetValue "dotXSIExportOptions.animgeom", False
SetValue "dotXSIExportOptions.animcam", False
SetValue "dotXSIExportOptions.animlight", False
SetValue "dotXSIExportOptions.constraint", True
SetValue "dotXSIExportOptions.custompset", True
SetValue "dotXSIExportOptions.keep_shared_mat", True
SetValue "dotXSIExportOptions.textures", True
SetValue "dotXSIExportOptions.txtfiles", True
SetValue "dotXSIExportOptions.constraint", True
SetValue "dotXSIExportOptions.envelope", 1
SetValue "dotXSIExportOptions.ik", 1
Let me know if you want the full script.
Forgot that if I import from another modeling program, XSIs explorer has Import Options saved I need to delete.