Yes, but we're talking about arbitrary categories here, there's no reason they couldn't board PM/GM before paid C+.
Well, sure. Works for me. But by the time all the pre-boards, PREM/DM’s, PM’s and GM’s have boarded, paid C+ pax would be justifiably peeved at being behind half the plane when they thought they were paying for “priority” boarding. Maybe DL could change C+ “Priority Boarding” to “Preferred Plebian Boarding”?