I would like to hear from you what kind of changes GSX causes to P3D files, and how i can restore them to the original condition.
GSX doesn't make any changes to any of the P3D files, with the exception of the addition for the lines that call its needed modules in the DLL.XML file ( the Addon Manager ) and in the EXE.XML file ( the Couatl exe )
The GSX installer will check your DLL.XML BEFORE doing any changes to it. It calls the standard XML validation routine that comes with Windows so, if that one reports the XML is corrupted, it IS corrupted, no question about it.
If the DLL.XML file is found corrupted, the installer WON'T TOUCH IT, but it will offer YOU a CHOICE between:
1) Aborting the installation, so you might try fixing the already-corrupted file yourself
OR
2) Starting from scratch with a *new* DLL.XML file, that of course, will contain ONLY the lines needed by our software, and nothing else.
If you chose option #2, it's normal that, if you had *other* 3rd party modules in your old (corrupted) XML file, they won't be present in the new one.
No, the installer won't try to "fix" or "merge" your old file with a brand new file. Brand new means exactly that: an empty XML with JUST the FSDT modules inside.
OF COURSE, the installer is not so careless to allow you to choose a potentially dangerous option #2 (you might not clearly understood what it means...), so it MADE A BACKUP, named DLL_XML_Before_Addon_Manager.XML in your %APPDATA%\Lockheed Martin folder.
So, it's not possible to do any "harm" with the GSX installer and, in the worse possible case, you have a backup.
So, if your OrbX airports needed addon modules in the DLL.XML, and you chose option #2 after the installer warned you about your DLL.XML being corrupted, is to be expected the sceneries depending on those modules wouldn't work correctly.
But of course, reinstalling the sceneries SHOULD fix the problem, because their installer should hopefully restore their needed lines and re-enable their modules, which were removed after you chose option #2.
If they don't, even after reinstalling, than I'm afraid there's nothing we can do and it's a problem you should report to the developers of those modules. Again, I confirm that, other than adding its lines to the XML files, the GSX installer doesn't change ANY P3D file.
We never had any previous report of known incompatibilities between our modules and OrbX which, considering how popular both GSX and OrbX sceneries are, should have surfaced by now.
It's also possible ( we have seen cases of this ), the problem is neither GSX or OrbX, but the presence of ANOTHER 3rd party module that, for some reason, is causing conflicts with the Simconnect library (there are several versions of it, all installed at the same time) needed by almost every module out there, so you might try checking this thread for more informations about this:
http://www.fsdreamteam.com/forum/index.php/topic,13165.msg98428.html#msg98428