UA256 tomorrow (Monday) DEN-SFO had equipment change. B788 downgauge to B763 2cl (with new Polaris). I received a call from a United rep this afternoon asking to switch to another flight in confirmed F (I was originally in M with instant upgrade cleared). I switched onto DEN-SJC at 8:30am. My reward was $500... which is personally my first VDB since March 2017.
Finally!
At the end of the ordeal, first was over by 5 and economy by 3 according to the phone agent. I'm glad I put my name on the VDB list when I checked in online earlier today.... which likely put me first in line to be called with the offer.