My invite finally appeared and I'm switching to New Blogger today. However, judging by the experiences of other people with big blogs, since this blog post is one post shy of 400 posts in total I think this might just take a little bit of time(!) and/or there may be a few problems. So if I don't reappear for a bit that's why.
I've got all the posts backed up (in both blogs) and all the template and side column links backed up in html - so here goes!
[UPDATE: Well that didn't take too much time! The blogs converted over really easily and adding my tweaks to the side bar column was really easy given that most came up automatically anyway. The rest I just added back - using the add-in html module - from the copy of the template that I'd saved in Word. Just got one small niggle to sort and then I think I'm there.
Do let me know if there's anything that looks odd and/or you're used to seeing and can't find and/or the change is creating problems for you]