The Junkers style control surfaces don't appear to have been used very much, at least not to my knowledge. Any thoughts?
There is a simple reason that the Junkers type control surfaces went the way of the DODO bird.....
They create a lot of extra drag with no benefit when they're doing nothing, much less when they're deflected.
When conventional surfaces are "at rest" they create no extra drag. Ailerons that're in a conventional wing are simply part of that wing when they're not working. With Junkers ailerons or flaps, they're extra drag that wouldn't be there when they're doing no extra work. After all, the Junkers wing is simply a conventional wing with "unmovable ailerons" isn't it. But with another entire little wing stuck under it's trailing edge.
An airplane with Junkers type control surfaces is slower and uses more fuel and weighs more than that airplane would be with conventional surfaces. You'll notice that the Germans didn't produce any airplanes with that style surface after the few that used them.