A couple of spare moments meant I could download the latest WordPress 2.0.1 version and upgrade.
After a complete site link check I found I had feed problems due to my permalink structure, as well as one or two other annoyances – like stale links throughout the blog. All are now rectified and with any luck there won’t be any more upgrades for a bit.
Now that I have completely developed my own theme, upgrading is much easier – from the date modified attribute on the new theme files I can tell which of my theme files to update also.