I was wondering, might the change upset the scripts I use that automatically put my mythbuntu backend to sleep and wake it as required?
The conversion to UTC requires significant changes to the database, and may be problematic for some users. MythTV will automatically attempt to perform a database backup before any schema update, storing the dump to the current user's home directory, or any storage path MythTV has been informed of, so that if anything goes wrong in the process, the database can be rolled back to the previous functional state. If MythTV cannot find anywhere with write access to store the backup, it will proceed with the update anyway, so users may want to perform their own periodic backups just to be safe. Refer to Database_Backup_and_Restore#Quick_Start for more information.