Yes, the files are compatible across software versions.
A few caviats: If you've added any DP8000 nodes to your show, it won't load on software versions older than 3.0.0. If you need to go to an older version, you'll have to remove any DP8000s and convert all your patching to use DP2000s before you load it on 2.x. The Clone DP feature makes this easy.
If you've used features like list rate, clock triggers, or mark cues and you go back to an older version that doesn't support these features, they won't work. The show will load a run, but cues won't mark, etc.
If you're going back to really old software versions, especially versions that don't support the v4 fixture library, the show might not load. In general, if you have a show from the 1.x days, you should save a copy of it before you try and load it on 2.x or newer just in case there are issues (it's a good idea to keep a copy any time you move to a new version).
