I don't buy linkage in kit form, I more often then not make up a cable system depending on how things are going to be run. I have a few items used for control line planes like bell cranks so if something like the Dubro is needed I have the parts on hand to make my own. I keep a lot of piano wire on hand in a bunch of sizes so I have often use that with bends or Us in them to get to the throttle arm. I do have a photo of the Dubro on my wall to remind me of a different way to do the linkage set up.
Gene