I just upgraded to BlogEngine.NET 2.5 and found the process to be fairly straight forward. The upgrade instructions suggest that you start from a v2.5 installation, and then copy your existing data and settings into the fresh install. I did this and then copied some additional files that were not explicitly mentioned in the instructions. Most of these were files that I added myself to customise the blog.
It’s always a good idea to separate content from behaviour, and this is the reason I don’t like the idea of adding
rel attributes to my anchor tags in order to support Lightbox. I may decide one day that I want to use Highslide or another library instead, and I certainly don’t want to massage the HTML of my existing posts or put in hacks to support the new library.
It's taken longer than it should but I've finally got around to setting up a blog for myself. Because I find it simple and extensible, I decided to run the blog using the ASP.NET based BlogEngine.NET. The project is run by Mads Kristensen, and he and the team are very active in bringing new features to BlogEngine.NET.