none of the tools works seamless in terms of "all you do in 3d suite x will be ported to MED". all modelers you mentioned support exporting to fbx. so geometry will always be ported. lightwave fbx has known issues with bones (will be null-object related), but you can purchase a "native" mdl exporter from GreenBriar, cinema4d fbx is know to be non-autodesk compliant and may cause problems with other applications, such as 3ds max. xsi is a rather safe choice for fbx, thanks to crosswalk, it supports many other export formats. do not trust the max and maya mdl exporters on the conitec download page, they are outdated. fbx is the way to go here, too.

however, special and editor-specific settings like materials, multi-uv-setups and procedural textures along with nurbs, patches, splines etc. will always cause you some headache and will force you to find you own workarounds. there is no such thing as a 100% carefree solution.