We did a successful migration from SFDC to Dynamics CRM last year. It took some time and was quite painful, but we had good support from Marketo and Microsoft. In the end, we learned a lot, and Shad wrote up pages of detailed notes, tips and gotchas in this post:
https://community.marketo.com/MarketoDiscussionDetail?id=90650000000PezUAASBottom line, our combined solution works pretty much the way it did in SFDC. We are missing a few features promised from Marketo, such as supporting the "add to campaign" feature of Marketo Sales Insight, as well as the great reporting and dashboarding capabilities in SFDC.
I'm sure Shad would be more than happy to answer any specific questions you have if you add them to the thread above.
And, we definitely would like to connect with other Marketo-Dynamics users at the upcoming Microsoft Convergence conference and/or Marketo Summit.
-Carl