We have new Marketo leads that are connected to existing SFDC accounts. We also have new Marketo leads that went on to be new SFDC accounts. We feel that marketing can say lead/account genesis from Marketo are ones you would never have and therefore a bigger impact. This is compared to an existing account where marketing only influenced closed/won business.
I think I can do this for a single contact with "person created date" being before the "SFDC create" date. Is there any way to get to all of these into a report? I would also be open to combining a SFDC campaign object with a Marketo smart list.