I recently migrated this blog (which runs on Blog Engine.NET 2.8) from the XMLProvider to the DBProvider. I followed the instructions here: http://www.nyveldt.com/blog/page/blogenginenet-provider-migration which almost worked, but I had to make a couple changes:

BlogService.Provider.FillCategories and BlogService.Provider.LoadSettings requires that you pass the current blog, so those lines just got changed to

BlogService.Provider.FillCategories(Blog.CurrentInstance)

BlogService.Provider.LoadSettings(Blog.CurrentInstance)

Then, I had to manually update the GUID of the blog itself in SQL. Basically, after you run the DB create script and run the migration page, you grab the id of your old blog and update the bd_blogs table:

UPDATE [dbo].[be_Blogs]     
   SET [BlogId] = 'your new id'
WHERE [BlogId] = '27604F05-86AD-47EF-9E05-950BB762570C'
GO

And, walla, now I’m running on SQL Server!