Well, these programs each have their own way of doing things, of course. Like Generations will let you assign a source to nearly anything you put in there. Even notes can have sources. But when you save to a .ged if there isn't a standard for that note having a source, then it won't be recognized by the next program that you use to read that .ged file. And if you make up your own tags they might get included in the .ged but still won't be recognized by another program. Maybe not even by Generations if you were to try reading a .ged it had created. I'm not sure about that though, since I haven't tried it.
I've been frustrated by this for awhile now. I want to go to another program, but don't want to have to re-enter everything by hand. And I lose a lot when importing a .ged into another program especially the notes I have written for individuals.
There is a program that will read a .uds file, but I can't remember the name right now. I tried it once under windows and it did work, but wouldn't run under Linux so I dropped it. If I were going to use windows, then I suppose RootsMagic would be my choice after Generations. Anyway, you can try a lot of these for free and see how each imports your .ged file.