Sorry Paul, but it has been well hammered on in this forum that 4.5 was a massive update, and it would break a lot of applications, plugins, themes and forums.
My forum is heavily modified with custom Themes, Pages, Applications and Plugins, and I knew full well what I would be getting myself into before I started. I even told my forum members a couple of months back, that when we started the updates there would be some disruption to the forum.
I update, because I have seen first hand what happens to a site and software when they are not updated. My brother co-hosted a pretty large Unix site which was built on v-Bulletin. The software wasn't updated past version 3. They had a ton loads of custom code written over a period of 10 years, and when they finally decided to update, they either had to start again or upgrade all their code to work on the newer version. I offered to give them a hand, but once I saw the state of the code, I decided against it.