Experience migrating recurring contributions from Raiser's Edge to Civi?

[CiviTeacher.com]

An organization uses Raiser's Edge to manage 4000 recurring donors per month with iATS as their payment processor.  The credit cards are encrypted within Raiser's. 

They are interested in migrating this data away from Raiser's Edge to have it managed exclusively by iATS.   iATS seems willing, but exporting (securely) all that data is something Blackbaud hasn't offered a plan on yet. 

As a bonus, we'd like to build the recurring plans within Civi so they can be managed by CiviCRM.  But this is a 'bonus' step.

Has anyone attempted this?

[adixon]

How did this go?

I'm migrating some recurring payments from other providers into iATS for two clients, and at least in theory, CiviCRM can do the recurring payment management when using the new plugin, though 4000 would be a lot of entries to enter manually.

I suspect I'll end up writing a batch importer, but if you have any useful hints from your Raiser's Edge experience, let me know.