It knows it as well as AES? That surprises me as Oliver supplied specially constructed BGLs.
That's because AES works on top of a technology that was made many years ago ( I think the basics predates FS9 ) by mr. Maurizio Gavioli (who made the Vistamare module ) and it uses the .BGL as a container of custom commands, outside the .BGL SDK, to allow interactivity, in a time when there was no Simobjects, no Simconnect, and no official SDK even. The original .BGL language even had some instructions that allowed to embed x86 ASM language inside a scenery...go figure...in the '90s, you really needed an ASM hacker to peek inside MSFS.
If that's the case why is AES so expensive? I appreciate that's of no concern to you but you'll understand that having invested over 100UKP in AES credits it's not an easy decision to dump it.
AES is expensive because it requires quite a bit of work to support an airport. We preferred the approach of trying to make GSX smart enough to work anywhere, without charging for it. Which means, every improvement in GSX, will any FSX airport, past, present and future.
I've not been able to see a difference between the two if I'm honest.
That's the biggest compliment you could have made to GSX: having the "generic" method to stand on his own against the customized approach you pay dearly for it. Yes, there IS a difference, and it's price...
I could just use GSX Pushback but then what am I using in AES? Hardly anything with a lot of money effectively wasted.
I said: "can't you simply NOT call GSX Pushback ?". If you really want to use AES Pushback "because you paid for it", just NOT call the GSX Pushback. The only thing that would do a "Pushback without Pushback" option would be, as I've said, the recall of the attached IF you called Deboarding and then didn't do Boarding for some reason.
I don't start another flight immediately after a previous one so that doesn't apply.
That's precisely my point. It means you don't even have to worry of having vehicles attached from a previous Boarding, which would be the only case in which such feature might be useful.
Which means you don't need the feature and, if you want to use the AES Pushback instead of the GSX one, just don't select the "Prepare for departure and pushback" menu option in GSX.