My back, i forget i put it to "z" as gonna use "x" for a mechanic i discard, a drop down.
I never put jump in up if i can avoid it. in the long run only work in fighthing games, it limit much combination of keys.
Besides you can play with a gamepad , its not the best left a idle hand(talking about it i still have to find somethig for the second phase may be a turbo)