Downloaded GSX recently to test it out, as I like what I saw in videos on Youtube.
It's only in trial mode atm, but plan on purchasing it in the next week or so. I flew to EDDM, one of the airports that work in the trial, and was suitably impressed. The marshaller, however, was not that impressed with my parking, lol.
Not quite sure how the jetways work, a GSX message displayed reminding me to activate the jetway, so I did, but then said something about the parking stand have a "default jetway". I have only tried GSX once on arrival and departure from EDDM, and haven't read the manual yet, so apologies if it's explained there. That wasn't an issue to me, just something I noted, the catering and baggage services worked just fine on arrival as well as when departing. I fly the PMDG NGX, so refuel via the FMC and not GSX services.
My favourite part of GSX is the pushback that aligns you correctly on the taxiway, would buy it for that alone.