Last week I was at DEN RCC East and they looked at the Pres Plus MC and shrugged. No joy on my OnePass number either. But scanning my boarding pass (printed at home) got me the green light.
Yesterday at DEN RCC West, they poo-pooed my boarding pass, but seeing the Pres Plus MC got me a smile and a "what's your OnePass number?" and a subsequent green light.
So YMMV.
If you go, be sure to request a t-mobile wifi pass (free) since the RCC wifi is based on the RCC membership number.