The main advantage of using GSX instead of the TAB-S SODE menu, is that GSX will pass its own door configuration for the selected airplane to SODE, so you won't have to worry about keeping the SODE airplane database up to date and, if you edit the airplane configuration in GSX, the changes will be available to SODE too.
Every scenery using SODE (provided it was made using SODE 1.3 and above) will have its jetways recognized by GSX so, it's best to just use GSX, and not worry about the SODE airplane data.