I am trying to get support to use your tool. Can the order of syncing be reversed to go from Constant Contact to SugarCRM?
The best way to get fast support is to post as you did here:
Our CRMs win in SyncApps so that your master data is always in Sync with your Email Marketing Provider. We do have Enterprise level plans for custom SyncApps which might be what you are looking for if you are trying to migrate data from Constant Contact to SugarCRM.