Didn't know about the sliding tether until seeing this thread. Just looked it up
HANS Sliding Tether
Looks pretty simple to install. I've got one of the older models but it looks like it can be upgraded as well.
I agree that in the RT's there are very few situations where you're aware of the tether limitation and with the sliding tether it all becomes a non-issue. Clever upgrade. Bravo to HANS for building the even better mouse trap and making it adaptable to most previous models.