For all extensive purposes the MER is truly what you want to measure at this time as most return carriers are now QAM signals. However, that being said the DSAM-600 is unable to properly lock onto a digital carrier with true data therefore this number is an estimate in my opinion. The best test set-up you can currently use is a HUKK meter with either a sunrise or trilithic analyzer at the receiver.
This is CABL.com posting #289465. Tiny Link: cabl.co/mbnsX