I'm really not sure why so many people have problems with so many various software updates on OSX. The Roxio update went exactly as expected, as follows:
I logged into my machine under my admin account (which is also what I install ALL my software as - everyone IS doing that, RIGHT? - you KNOW that ADMIN is NOT for everyday use, right?), and ran the updater.
It asked me to identify the version of Toast I was updating (it even gave me the option to choose the copy I had duplicated to another partition as a backup, in case the naysayers where right), I selected the version in my Applications folder, it updated all the files, and placed a copy of the NEW app (Toast 5.2) in the same folder as the 5.1.4 version, which it left there. I removed the 5.1.4 app package (thought there was no apparent need to do so, other than for reducing redundant apps), and gave it a whirl.
I worked exactly as you would expect. I logged out, logged in as my user account, tested it, again... perfect. Now with the added features Roxio promised (ie: CD-TEXT et al).
No need to delete preference files, no removing previous versions. It just plain worked.
If you are going to bag a piece of software, make sure that it deserves it. And make sure that you, the user, aren't the cause of the problem.
So ask yourself: Are you STILL only running one account, ADMIN, on your OSX machine, and tinkering with it every other day?