Eh. I'm considering migrating this blog over to MoveableType. Should be straightforward enough, judging from the manual (and I'd do it now if I had FTP access), and I'm getting tired of Blogger's "quirks".
One thing I don't like though is, I'm going to lose the comments I have on BlogBack... :( I'm not bothered about the account, even though it's one of the few unrestricted free accounts and it's old and I have lots of comments on it and... okay, maybe I'm bothered about the account, too. But meh.
Can you see me going through each single entry in my archives, finding out which ones have comments, and copypasting the comments into a new comment for each archived entry? ._. Meep. Okay, maybe I'm actually switching in the weekend, or as soon as I have some time to iron out all the wrinkles and tiny problems I'll most likely get from switching... I could sacrifice comments, but a lot of them I like and want to keep... ._.
Perhaps I'll wait until I get switched to this new version they have... see if it's any better. If it isn't I'll switch.

Switching to MT is sort of weird at first, but I think you will like it. I made the switch from Blogger to MT about 3 years ago, and it's been great.

Also, about your comments, have you written the BlogBack people to ask them about exporting? Also, you might want to go to the MT forums at their site and ask. There are people over there that seem to be able to solve any problem at all. :D

I've been using MT for a few weeks for my photolog, it works great, it's why I'm considering making the switch... hehe.
Not the first time I've used a non-Blogger blogging system, I'd switched to GreyMatter for a few months a couple years ago, but it horribly crapped out on me, just stopped working.

I looked through the Blogback site and it appears that exporting of comments is only for the people who pay extra for it. And I somehow can't see myself going to ask my father to lend me his credit card so I can donate to a site so I can export the comments and stop using said site... :P
I could try asking on the MT forums I suppose... would you believe I hadn't thought of that? :p