If I'm not mistaken, I could be, there is a way to drop back to the .5 version. As soon as I find it again, I'll post it here, unless someone else beats me to it. Also, I heard that it will wipe your phone, not sure about that either.
Churro, use MyBackup to backup everything, or Titanium backup. After you root you can restore all your apps. Also if you sync with google then your contacts /email will already be there.
install the .5 ruu and then you can root from there (like the linked thread says) if your still unsure, there is a good thread on reverting back and rooting the .5 install, very easy to follow over at xda