As I mentioned in the other thread, I'm looking into using points to stay at JW Grosvenor House. I noticed that if set the # of guests to 3 (to include my 8yo) then it requires me to pay an extra 50GBP/night to bump up to a Superior room. That prompted the titular question in my mind. Since the MegaBonus requires a "paid stay" does this sort of hybrid Reward+supplement count?
No. While they count toward annual and lifetime elite status, they do not count towards Megabonus. Just completed 2 paid nights and 5 points redemption nights, where we paid an extra $100/night for a Griffin Club room upgrade at a JW. The redeemed nights counted toward status earnings, but not towards Megabonus.
As others have pointed out, they do not count. If, however, you paid for one night of a multi-night stay and used points to cover additional nights, the one paid night would count toward the MegaBonus.
I'm guessing when the Cash + Points rolls out later this month, those nights will not count toward the MegaBonus either. The terms and conditions already states that "members will not earn points on the cash portion of the NEW Cash + Points." It does say the elite night credit will be earned, though it will likely show up as an elite night redeemed since it does involve the redemption of at least some points.