I notice the new HCR's come with tethers. Aren't the DESS keys on Doo's tethers as well? But I agree that they should all come with them - be it mtn sled, 120 kids sled, 600 two-upper-deluxo or whatever.
The problem is when they tangle with the handlebars (or trees) during "less than graceful maneuvers". Then people get annoyed and they aren't attached anymore - similar to how kill switches on the handlebars seem to end up with rubber bands under them, neutering their functionality. Teth-air has a decent solution, but it'll probably be a while before the costs come down so that it's a no-brainer.
A good question is where to mount it so that it isn't tangling all the time? I was thinking of putting one right up under the mountain bar somewhere on the top of the steering post. Should keep it out of the way there maybe?
I attach mine tot he front of my klim jacket. There is a spot to attach there. I never, ever had it snag on anything, or have it in the way.
As for other manufacturers, Don't they have a throttle override on them, so if the throttle sticks and it doesn't press a sensor at the throttle lever(which only happens when there is tension on the pivot point from the cable) ?
Yamaha had the T.O.R.S. years ago,