I don't know if I'll ever use a snapshot. I just wait for the updates. Are snapshots worth installing and playing with the risk of encountering possible bugs? I don't really want to be a tester, so am I right in thinking snapshots aren't for me?
I usally have the same fear as you but, if you read what it says for this snapshot it isnt like normally downloading a new snapshot. You just download the new launcher and It does it for you. If you want to go back to 1.5.1 than you just open the normal launcher other than the new one downloaded. Its , simplistic, and very easy to switch back. No more having to make copys or fumble around in your .jar.
1.5.1 Snapshot Ready for Testing