Unupped, I would definitely do gravity pendulum and time mark for that deck. Getting 2 or more pendulums in the first hand will let you play a momentumed dune scorpion on turn 3, whereas the time pendulum and gravity mark requires 3 pendulums or more right away to do the same thing. Fully upped, I'd do it the other way around, with time pends and gravity mark, for the same reason; you can get the momentum scorpion out faster with a poorer draw.