Once checking in at TUS for HP flights to LAX in the morning the ticket agent also checked me in for my CO red-eye out of LAX that night. (The TUS HP ticket counter also does CO) Once at LAS the CO ticket counter refused me check-in 4-1/2 hours before my flight, but the HP club agent had no problem checking me in.
Here in Arizona OnePass is going to be more like OneHalfPass after HP's gone.