Curious how others are doing this? Are you measuring only from Marketo and possibly using revenue model/RCA? As we are also wanting to report this in SFDC - so wondering what may be best way to do this and what others are doing? HIdden fields that are capturing this information in SFDC? We would like to do the same for Sales Contacted Leads (SC) and SQLs.
I consider everything that is pushed into SFDC an MQL. After that point SQLs and other measurements are done by lead status/conversion/opportunity within SFDC.
It just makes life easier to restrict the CRM to only MQLs, so that way if I want to pull a report in Marketo of emails sent for something and I want to know how many MQLs I hit, I can filter it by "SFDC Created Date = Not Empty"