Render to texture in max can be annoying as there are options to create shell material automatcially etc.....

In what ways are the UVS wrong in GS?
The best way I find in Max is to use UVW unrwap modifer and use one texture only....
Its really important not to overlap the UVWS as when you bake the textures it, it goes into a real mess------

Once youve baked, I usually find its ok in MED......