I never tip extra for any rewards program, I tip soley on service provided.
A few days ago I was at a nice brazilian resturant with excellent service, did not have to ask for any refills, glass never got less than 1/2 full. I tipped heavily, and typically when I tip I pay for my meal with CC but tip in CASH, unless I do not have any.
Less chance then of them not getting it properly, like happens sometimes with credit cards.