The general idea for doing what you are doing, i.e. fitting a Jensen transformer by tapping the outputs, is attended to by various schematics at the Jensen site.
Not sure what your getting at here. The only way one could know that is too look at the wiring of the unit with one in it. Also, what happens if at sometime something (that has nothing to do with the DI) goes wrong with the main circuit? Then you or your tech have to spend quite a bit more time troubleshooting than if you had the Demeter schematic. Schematics should be included with electronic devices.