I flew a short regional round trip a little over a month ago and had mixed success as Silver. On the departure, the CRJ9 went out with seven in F (1 C/D was blocked and occupied by the FA). One Pax was upgraded after the door closed, and six (including me) remained on the list with no upgrade. I was in 5D with the row to myself, so with no PDB service, I considered it the same as First .

The return flight was considerably less full, and I got the upgrade with my FF companion, and there was one empty seat left in F when we pushed back (with nobody on the list).

Perhaps this has just been my experience on the routes I take, but it has seemed to me that Delta is running more CRJ9's on my regional routes, rather than CRJ2's, which I am not sad about.