A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
Call.
IME DM agents can assign blocked seats with the understanding that you can be evicted if someone needs them.
Assuming you're correctly confirmed on the flight, I'd go with no seat rather than begging for a very bad middle seat. What you're assigned at the gate can't be any worse and as a DM you're extremely unlikely to be picked for an IDB.