1. In 2006, I completely converted one of my larger forum's sql tables collation to "utf8_general_ci" (UTF-8 Unicode) and never ran in to any problems - not even password problems.
I can imagine password problems would be the worst case scenario, with users unable to log in.
Just a few questions if I may about how this worked out in your case:
1. How large was your forum at the time of the conversion (let's say GB-wise for a MySQL dump to get a general picture)?
2. How did you go about doing the conversion - what exact script/command line/etc. did you use for your particular charset conversion?
3. How did you run the actual conversion? Was it via something like PHPMyAdmin or did it run as just a SQL database query?
4. Did the entire conversion script/process take a long time to run?
