I'm going through this right now - all my old content is on blogspot.com, and I want to move to my current blog at mydomain.com/blog. I'm sure there's a way not to move all these article URLs by hand, but then I have to go and make sure all the inline images come through as well, which were uploaded to blogspot directly.
I mean, I was just looking for a quick solution in college so I can't blame myself, but I do want to run back to 18 year old me and kick my heels a bit for creating such a big chunk of technical debt I doubt I'll ever actually fix.