Testing - The current testing version based on "master" build
The testing tree is for IPFire power users who want to use and test the latest features that are going to land in IPFire. You will find a Core Update in there after it has been announced via the IPFire Blog. The Testing code was reviewed and tested by some people in small test environments and is now ready to be tested by more people.
Unstable - The current testing version based on "next" nightly build (may be incomplete / dangerous).
Everything that a developer does goes to the development mailing list. Patches are reviewed and fixed there and then selected by Arne for going into the next release. That process is important to only select patches that have been seen by enough people and pair them together to bake a nice update. This tree is called unstable and everything in there is literally that. Developers have tested the code, but it has not been tested by a wider audience.
How to switch
The Testing repository will appear after an announcement via the IPFire Blog. To participate go to the WebGUI menu IPFire > Pakfire and in Pakfire Settings, click the Repository drop-down, and pick Testing. Then click Save.
Unstable releases are on an ad-hoc basis and are updated during a nightly build. There is no Blog announcement. To participate go to the WebGUI menu IPFire > Pakfire and in Pakfire Settings, click the Repository drop-down, and pick Unstable. Then click Save.