LucaMs,
Are you referring to layout variants or layout as in design? if it is the first then let me tell you that i tried 2 layouts and coded for each one as explained in my first post, the result in the emulator was fantastic ,each layout variant look beautifully, but not so much when tested on the real device, i did solve my problem by using the method above.
now when talking about layout in the sense of the design i do have 1 landscape layout and one portrait layout which i load according to screen orientation, but the main point been that the layout for portrait is one adaptive layout for all screen sizes and resolution in portrait mode as model in my script as is the landscape layout for all displays in landscape mode, so you see instead of having 2,3 or 4 layouts for different screens plus the code to properly handle them multiply that by 2 if you account for a portrait and a landscape for each screen size that you target.
So in my particular case i believe that the designer script approach is more efficient and uses less code and is much more cleaner to maintain. Hope it clarifies the point explained here.