Here is an alternative approach ... Arrive early enough so that you can enjoy a full 2 hrs in the CCR, assuming that you will leave 1 hr before the scheduled flight time.

Then, if it turns out you have B-gate departure, leave the CCR 1 hr before departure. Take a gentle (no need to rush) walk along the walkway (your body will thank you for it given the upcoming flight), and recover from the exertion with a well earned drink in the B-gate lounge.

Sure it is not the CCR, but 2 hrs is still enough time enjoy the place, and being able to walk leisurely to your gate from your second lounge stop in just a couple of minutes has a value all of its own.

Of course if you get a C-gate the equation is not so simple - then given your concerns I would on balance suggest to stay in the CCR in that case and leave at T-40 (especially travelling in First).

Note that you can ask at the desk about the gate assignment - very often they will be able to tell you some time before the information appears on the screens (with the caveat of course that changes are always possible).