I've used just about every type of throttle lock made, on many different bikes. It's not like you can't override the throttle. Are they perfect? NO Do they work in a pinch? Yes. Sure it's easy to WANT to think all the wrong things about them, but the bottom line is, if it works for you so be it. None of the locks I've tried will maintain a given speed for very long. My experience is that it is enough time to shake your hand out, rest it for a minute or five, and get back to riding the bike.
I will say that they are handy as hell for their 'instantaneous' activation. Many times I'd like to give a friendly wave to fellow travelers and I can't get my cruise set fast enough. With the CAT ring, it is ALWAYS set. None of my experiences with the O-rings have ever led me to one of those OH $hit moments like I have had with the cramp busters. But that's just my two cents.
Tcro- you roll the oring on the bar end when the bike is stationary. When at speed roll it into the space between the grip and the bar end. It's hardly a seamless operation, but works well enough. You can then adjust your speed to your needs. To remove just roll back onto the bar end. Hey sounds like you can get the rings for nada, so it's worth the experiment.
D