I have been investigation on this
Zapier is working in some developments but checking it with the Marketo and Zapier team this is the feedback:
They were clear that they’re focused on single-event scenarios and only support uni-directional cases. Another limitation is that they don’t yet support ‘upsert’ into Marketo, which basically means the ability to update an existing lead rather than only creating new leads. I think this one missing feature could be a blocker when writing into Marketo from CRM.
We are working with them on building out a marketo integration but in the meantime I can share this link to the beta offering and the customer is welcome to use it and provide feedback to both us and Zapier: https://zapier.com/developer/invite/33716/7c768fa276ae3d1e4db3f1338a82d7a9/
Typically customers want bi-directional sync. Since Zapier isn’t designed for this use case, the customer would have work around this and might be able to approximate a solution.
Hope it helps
If anyone get the integration , please tell the community!!
The alternative is migrate to SF but I am very happy with Insightly