It's good for kids to hang on to or to pull your sled over on the shop floor. Otherwise very little use for one. If your handlebars are at about belt level you will have no problem with leverage. Ride wrong foot forward when sidehilling. Check out Bret Rasmussen & Chris Burandt new video "Schooled". They don't use them. Lefty or mountain bar.
You got it, PP. Buy the video SCHOOLED. These guys reinforce the dis-advantages of using a mountain strap and having a lefty hanging off your bars. Learn to ride without, take off the training wheels and you will perform better in the end. It is all weight tranfer left to right and moving forward/aft on the sled. I am guilty of having and using all this junk in the past but have learned to make it happen with the sled and myself, not using the cheats.