I've done it 8 times this cycle. I tried DP1 on my dev iPod Touch 5th generation. It was so unstable that I restored back to 6.1.3. I tried DP2 on the Touch and my dev iPad 2. It was better on the Touch, but I restored both to 6.1.3. I didn't think either was stable enough to provide a meaningful testing platform.
Finally, with DP3, I've gone back and forth a couple of times on both devices for testing. Each time, iOS brings back all the apps and settings from the last backup made before the restore.
Steps
1. Back-up to cloud and computer (just in case).
2. Option-click "Restore" in iTunes and select the relevant IPSW to install.
Why would DFU mode be involved? You shouldn't need that unless something has gone wrong somewhere.