Nobody knows. There is a PD waitlist, but we don't know anything about it other then it ranks behind the PA and PB. They may go on the PD, or folks using those instruments may start to be added to the PB waitlist as their windows open (120/100/72/48 hours).

Again, once it goes to the DM, however, upgrade type no longer matters - just status, fare paid, and time added to the DM. As a 1P on an MUA, I have lost out to 1Ks on 500s (fortunately only once and it was the SFO-SEA part of a JFK-SFO-SEA run so I figure I got my miles worth).