Mail Chimp has pre-built e-commerce segments broken down by: Recent Customers, First-Time customers, Repeat Customers, etc. Does this work with the integration of an existing ECT site? i.e Will the old customer information automatically show up in their proper segments?
I wouldn't have thought so as just the email and name are synced with the mailing list. Feel free to put it in the suggestions forum though. Your support status needs updating too.