I had this conversation on Twitter yesterday.

That's fine. 37Signals is known for saying no to things in the interest of a better product. A migrator for BCX isn't exactly something that would add enough value to the product to warrant spending their time on it.

It's cool.

Don't worry, I got this

I built one. It only took a couple hours to throw together and clean up. It's super basic, but it did the job for me. It handles todolists with their todos and comments, but no attachments.