Email marketing- Contactology vs Mailchimp

I am evaluating whether to integrate Zoho CRM with either Mailchimp or Contactology (I believe the only two companies that are available at present with zoho). I have tried using zoho for emails and it doesnt work well at all.

I was wondering if anyone has experience with the integration of either system and can tell me pros/cons.

Specifically, want to know:
- Is integration one way or two way? ie can I mark in zoho automatically what emails a customer has received in mailchimp or contactology? Or is that only stored in mailchimp/contactology not zoho.
- How easy/seamless is the integration for a non techie?

Also, would be really interested in any best practices if you have them as to how to do this well!

Thanks,
Carrie