Well, I’ve upgraded without breaking too much. :)
As you can tell from the categories list, there are some differences in the way Strayhorn presents things that I’ve had to adjust in my CSS, and some differences I couldn’t fix. I’ll need to look at the subcategories issue a bit further. However, there wasn’t much damage done, and I’ve been thinking about a redesign for a little while anyway, so this might give me the excuse.
Anyway, I’m definitely recommending WordPress 1.5. It has a lot of new functionality that you used to have to either program in yourself or find a plugin to get. (Incidentally, the upgrade only broke one plugin, and that was a fairly new one released for the first time just before 1.5. I’ll have to see if I can fix it up.)