The G9 has excellent WB control so it would be better to choose between the 'standard' magic and the UR Pro. I'm sure the auto magic is intended for use with point and squirts without WB control.
I have a G9 and Ike and use UR PRO's with the INON UWL-100 w/a glass. I can fit and remove the UR PRO underwater which allows me the opportunity to shoot deep available light (without a filter), shallower available light (with the filter), w/a, macro and portraits (without the filter but with strobes) all on the same dive.
If you fit a magic, you will be constrained to available light shots within fairly tight depth limitations. If that suits your style of diving and / or subjects then go for the magics.
Magics are as cheap as chips so there is a good case for using these to try out available light filter photography.
There is plenty of reference information on both the magic filter and UR PRO www sites.
HTH, Tim