i always updated OCD to a newer version without any problems.

If you afraid of having trouble, back up your database and copy it to a secure location (e.g. on a stick) If it does not work as you expect it so you could reinstall the older version and import the backuped database.

The newer version solved perfomance problems on vista, and changed the mygenres.com support to racksandtags.com

I thought that there are changes in behaviour of A and B Sites so you can split or somthing like that. I never used that feature so im not really familiar with that