when we use the model importer included in GG it converts the model to dbo and dont include the x mesh within the file or the FPE . SO i do convert any 3d model i do refer the model in the FPE to the Dbo file and i keep the x model just in case .
the dbo is way smaller size than the x file and i think its easier for the engine to deal with .
thats is what i concluded
hope that was helpful
