Well, I've been using Moveable Type for about a day now, and I need to say that over all, I'm a lot happier with it than b2evolution. It's administrative interface is actually functional, it's templating system makes more sense to me than b2evos did, and the Widget system seems pretty cool.
Still, I have a few gripes. The templates that ship with MT4 don't actually use the Widget Sets system that they've built for it. I've gone ahead and ported this blog to using the Widget Sets, but I need to rework the widgets and the template to have different widget sets for different types of pages, and display them correctly still. Having to re-publish my site when I make template changes is different, but I don't really mind that much since it's a background process and keeping my blog in HTML files will just make it load faster later. Plus, this is infinitely more indexable by search engines than b2evo was (not that I care too much about that, but it is a potential plus).
As pleased as I am with MT, I would not have paid for this software. There is no way that would have been worthwhile to me. The only reason I allowed MT to be a serious contender in my search for blog software, was that it was going to have an Open Source version soon. I just hope that they don't fuck it up with a bizarro license and that I can easily migrate to the OSS version when they finally release it.