Grip deck pads are the only way to go..IMO
Much softer on your knees and when you go to stand and have the paddle across the board its much softer on your hands and paddle..and also offers better grip.
Wax is fine for regular surfing because you're only on your feet for a few seconds and most of the time you're just laying on the board.
I've heard many guys say they are happy to just use wax..Then after a few days they change their mind and say that their feet hurt and they need to get deck grip.
But then..Some of the hard core guys (Robby and Laird) seem happy to use wax..Maybe they have very tough feet..

..or maybe we're just soft..

DJ