Ok, thanks for the tip DLD. I added another pair of the biggest bars after your advice and actually I don't turtle anymore, curiously enough. Either way, progress is progress!
One thing that's holding me back is the amount of pain during higher tensions.... the bottom of the plastic ring (the part of the device that's right up against your waist) digs into the scrotum skin and soon creates a raw, chafing, burning pain. Usually for the first 1-2.5 hours during a high tension session, this isn't an issue, but after that it becomes too painful to keep on. This is easily remedied by switching to low tension for a few hours (figure I might as well get some extended healing in) but it's still a problem because 1) when it becomes painful at high tension, I'm often not in a position where I can duck into a bathroom to change the bars (on the bus, in the middle of teaching a lesson, etc) and 2) it seriously limits the amount of time I can put under tension
I've tried using various materials to cushion it, but nothing really seems to work
Does anyone else have this problem?