We are in the process of setting up Scribe for our Dynamics365 on-prem instance. We're not outright replacing the native sync ....yet... but we very well will likely do it eventually. We're mostly using it for the Sales Insights portion at the moment. Right now the only issue i see is the 50,000 API calls a day. Might not be an issue for smaller databases, but we have over 100,000 contacts. If we send out a rather large mailer and get a lot of activity, it could blow our calls. Make sure whenever you do a lookup in scribe to Marketo, you cache the results to avoid a double call on a record. Also might not hurt to add batching to the calls to limit records processed at a time. Apparently it makes things smoother too. Not sure i'd be much help beyond this though. ... View more