Mailchimp integration with syncing both ways?

Hey all

Our small non-profit organization has about 4,000 Mailchimp subscribers. Separate from that, we have 1,000 or so contacts in Salesforce (we've moved to the platform over the past couple of months, and managed to use it to conduct this year's Christmas mail out, so we're feeling like we're getting our heads around it). I'd like to integrate our Mailchimp with Salesforce so that we can run email campaigns and track their success within the CRM. Ideally, I think that means importing our Mailchimp subscribers into Salesforce. Also, I think they would fit best into that ecosystem as contacts rather than leads. I've looked at Mailchimp for Salesforce and Chimpsync, but neither seem to offer this functionality - MFS can bring them in as leads only and Chimpsync doesn't seem to sync in that direction. I am now looking at Cloudchimp, and it does offer the ability to move your subscribers in as contacts, but the problem is that there is some overlap between our Salesforce contacts and our Mailchimp subscribers, and when I tried a test batch Cloudchimp created a bunch of duplicate contacts... it does not seem to be able to recognize existing emails and merge the information. Does anyone have any advice for me? Either a way to make this work in either of these three apps or a new approach altogether? Thank you so much! All help is appreciated.