Army as a whole I believe. Most of our cases go to Seattle, but I think a few go to others. I'm at 60 days right now since receiving my unfit memo; O-3's and O-4's have a pending officer separation board (this Spring--potentially up to 30% reduction in force). They haven't announced the particulars yet, only stating that the proposal is with the Secretary of the Army, but I'm hoping mine follows your timeline so I can transition prior to any officer separation boards convening.
A few lawyers have said that the RIF shouldn't affect IDES, but IDES cases were considered when the SERB (selective early retirement board) met in August and they just said they would handles IDES on a "case by case" basis--whatever that means.
I can't imagine the hellfire and brimstone that would come raining down if the Army separated someone in the IDES process under the RIF instead. The only way I can imagine that the RIF for O's would affect someone in the IDES would be if you were to be found fit but then the board saw that you had a permanent profile (even a P2) and used that to separate you. That's partially why I stuck with the MEB as opposed to trying to rebranch- thought I'd get this painful process out of the way rather than wait for the Army to start separating O's with permanent profiles.