We're also "lite" members. I conduct routine audits (semi-annual currently) to verify that each loan:
1). Meets the Security Instrument Document Requirements. This includes appropriate template language, correct identification number (MIN) placement on the first page of the document, and the MERS phone number/address within the “definitions” section.
2). Validation of the Loan Data including accurate loan information such as the property address, registration status, occupancy status, lien position, and MIN type.
3). Ensure each loan satisfies the MERS initial registration timeframe and appropriate release timeframes upon payoff for those few that we actually retain.
And I do have a login as our "legal" representative so I can go in anytime and pull data to review. There are also a handful of reports which are required to be monitored by the FI so I spot-check those to look for anything suspicious.
I've only been conducting reviews for about a year (3 in total) so this is simply my interpretation from the MERS guidelines taking a risk-based approach for the possible errors I could envision. I welcome feedback from any others as to their audit program.