Just a note, I did not delete comments on any of the posts. Spam was getting out of control on some posts (even with Akismet installed) so I’ve removed the default Wordpress comment system and replaced it with DISQUS. A lot of sites use it, and it means that you can post comments across all of them with the same username.
Right now the comments that were posted on the default system are being imported, but I can’t really say how long that’ll take since there were over 50,000 spam comments.