[ProfessorM]

yes what Bruce said the lower the cutter, sled, the better control. You want the lowest height you can make it but still be able to get your hands on it and as heavy as you can stand it. Maybe take at least one sheet of that ply off the top of sled and put one under the base.
Make handles down kind of low so you can rest your hands on top of handles, fingers around handles, thumbs on back of sled, and wrists, and a little forearm will lay on base. Kind of a fonzy thumbs up, with the thumbs horizontal pointing towards each other. Make it comfortable as you are looking for downward pressure so handles up high are going to lead to fatigue as you won't be able to incorporate your wrists and forearms on the base. LOL making it sound like rocket science for cripes sake, sorry