I am working on a plugin to convert the wordpress database xml file to bludit's data structure and as you can see, it works fine (at least on my tests).
It converts Pages, Posts, tags, featured images, captions on images, Video/Twitter links to embed codes and creates an xml file with the comments if needed (for disqus). It doesn't convert galleries though. You can select if you want to convert media url (Facebook videos, Vimeo, Youtube, Dailymotion videos and Tweets) to embed code or leave them as they are.
I tried it with the Wordpress' theme test data. It supports the latest version (v2.0.2).
Version 0.1 (Beta)
Right now, this plugin is in beta phase and is ready to be tested. It means that maybe it won't work 100%, especially with non-latin characters in titles.
Get it from here. Remember to backup everything before using this plugin.
How to use it
Upload the plugin and enable it. Upload your xml file in the uploads folder (bl-content/uploads). On the settings, enter the filename, your discuss name, if you want to also convert the comments and check if you want the plugin to convert every video/tweet URL to embed code.
Keep your old data
You can keep your data (pages, photos, tags and more) from Bludit. This is currently a beta feature and you should backup your data first.
Merge Multiple XMLs
You can convert multiple xml files. To do this, upload first your first xml file and when finish with the conversion, upload the next file and change the settings for this new file. Continue this until you convert all the files you want. Do not disable the plugin until done, otherwise it will delete everything.
If your WP blog is in English, you can redirect your old posts to avoid loose your traffic. Open your htaccess file and enter this code below. You need only one, so keep only the line you need, based on your WP's permalinks settings.
REDIRECT WP TO BLUDIT
Month and name
RedirectMatch 301 ^/([0-9]+)/([0-9]+)/(.*)$ http://example.com/$3
Day and name
RedirectMatch 301 ^/([0-9]+)/([0-9]+)/([0-9]+)/(.*)$ http://example.com/$4
RedirectMatch 301 ^/post/(.*)$ http://example.com/$1
Remember to test thoroughly after making any changes.
Admin posts' page
Post with a featured image
Post with tags
Image with a caption
Post with video links converted