The vixen style rail will work on the HEQ5/EQ6.. The CGE bar is designed for mounts with the losmandy style dovetail saddle... the likes of obviously losmandy, some celestron mounts, astrophysics, tak etc...
The losmandy bars are definitely more stable, however for the weight of the C9.25 I dont think it would be needed... You can upgrade the HEQ5/EQ6 mounts to have a losmandy saddle,
www.admaccessories.com has a wide variety of options to that end...