Umberto, I personally love the .xml method of installing sceneries, as it makes a P3D reinstall so much easier. Unfortunately, I have run into an issue along with some other folks where adding new scenery will result in a crash when loading a scenario. There are several different reports of this on other forums, and the reported fix is to remove .xml addons out of the Documents/P3D Add-ons folder and manually add them to the Scenery Library. I could do that I suppose, but it sounds like something LM should address in a hotfix. It's been reported to them also, but their take is to refer the problems to the scenery developer.
To give you my specific example, I have 25 airports installed using the .xml method. When attempting to install airports from other vendors that require the Scenery Library method, the sim will load alright, but once I click ok to load the scenario the sim crashes. I then uninstall the added airport and all is fine again. Removing a couple .xml airports seems to fix things and I can add and fly the new installs okay.
I'm away from my sim computer for another week, but in my absence I can tell there's no momentum in identifying the exact cause or fix to these crashes, other than what I mentioned above. My question to you is if you've heard anything about these issues, and will any issues arise if I manually add all my FSDT airports to the Scenery Library? Thanks for any feedback you can provide.