I was scared, too, and put off upgrading as long as I could (until I really wanted it!
). Then I did everything carefully and closed my eyes and crossed my fingers . . . came out the other side and never looked back!
You will know (I think) pretty quickly if you have a bad unit, but since you have had yours for a while now with few (?) problems, chances are very good (95%??) that you will come through clean.
Let us know what you decide!