Yesterday, I was flying lax-jfk (waitlisted for y to bc upgrade). I showed the AC agent my bp and said I was planning on buying a day pass [I get reimbursed from Amex Skyguide program--once per month], but if my upg cleared I wouldn't have to purchase a dp; she didn't see that I was even on the upg list (I knew I was!)...since I was EXP, she let me in free and sent me upstairs to see one of the agents.
[The agent had to "refresh" my itn, to get me back on upg list--I was #1; I cleared at the gate.^]
A "side" note: if you buy a dp and later get the upg.--you will not get refunded...sort of a "catch 22" situation.