Right now there are no other importers that i am aware of. Other than the 3dsmax importer which was someones attempt to make an importer/exporter, However all it does is just import. It only works on "some" of the mesh's, and it crashes when you try to export a mesh. It works if you want to import, and study a vanilla sins model. No one else has tried to make an importer since that i am aware of. It seems to work better on older versions of max (prior to 2009).
There is a shareware program which i forgot what the name of it was that can open a mesh file. I question its reliability, and it is shareware, and will nuke itself in 30 days. Not worth it IMO just to view a sins mesh.
If it is exporting a mesh file that you are looking for XSI Mod Tool is free, and it works (though slightly more difficult than standard XSI). There are several tutorials on these board that show you how to do it that SHOULD have been stickied. I know the search function is virtually non existant on these boards, but if you back track you will find them. Look up the 7 Deadly Sins wiki. It has a few good tutorials.
