First of if you want to make money you need to get Pro Sites Trust me i run BlogLines.co.za and it is working so well that it is paying for my server.
Ok this has happened to me about 10 time over the last year.
1) you upgrade to the new pro site and all is working 100%
2) you go and play with some settings in MySQL Ie my.cnf oops you brake ProSites.
Reminder: Were are running Shar DB and i have also had the problem with Multi DB if you play on MySql it always brake THE COOL THE KICK ASS PROSITE PLUG.
Test it if you like
Now here is what i would love to see in ProSites down load setting tab this way next time i play with Mysql and yes i know i should not touch it but it is so nice to play with settings then i can just upload the setting for it and there we go all fixed
What i can say speaking about setting
These settings always stay in place
All the other settings are lost but i have done this about 10 times so it is easy to get it all working
Ps BIG UP for @WPMU DEF for having a Bulk upgrade System in ProSites