Well it took a while but I managed to get all three sites updated to Drupal 6.1. Riscy.biz and gonetogove.com actually have less features now than they did before because not all modules are up to 6.1 yet. I am also running patched versions of TinyMCE and Image Assist modules just to get by.
The biggest problem was that the update doesn’t work properly. DO NOT UPGRADE TO 6.1 WITHOUT A DATABASE BACKUP. I hosed Riscy.biz and Gonetogove.com because of this and had to restore an old database backup. Make sure you have a full backup first.
The problem is the migration of the image, file and node tables into the new format. The normal upgrade doesn’t care about the image module and removes an essential field.
I posted the details here:
This issue is caused by the upgrade procedure deleting the nid field files table before the image module update has a chance to get to it. I spent most of this weekend working this out. What you need to do (make sure you have a database backup) is to get ready for the upgrade to 6.1 then when you run update.php, click on the select versions button and set all of the modules to 'No updates available' except for image module. You will get lots of errors but now you can run update.php again but this time you need to go and select the earliest version 6 update for all modules except image.
If you need more details just leave a comment and I’ll get back to you.