If it was hurting your back, your posture was probably off. It's not something that's necessarily intuitive, but a workshop can teach you how to operate properly without pain. (or at least without significant pain, it may be a bit difficult for a while, but your back should strengthen)
Yeah, obviously I am a total amateur, so it was probably more me than the system. Damned hard operating a Steadicam, isn't it?! I was told, but it's hard to believe until you try it...