In all seriousness, if one has any concerns about updating their OS, it would be better to do a fresh install on another machine (or obtain a preinstall on a new machine), then move over your apps and data. Doing this will reduce the risk of issues exponentially!
I have been using computers since just before there were consumer available models. I am still learning things which I would think are not issues. My recent, which I think I posted on this BBS (age related reference) was a built into Windows reinstall of Windows, and how it offered no options NOT to wipe out the "program files" folders. So while not falling into "line" for installation of the software I license to others (I force install into a root folder), I had ignored this option for most apps I use, and suffered because of my complacency.