I'm wondering how these rock buckets would work for CUTs compared to root grapples. The Vernig small rock bucket weighs as much as a small root grapple even before you add a grapple to it and with the grapple would weigh about 150lbs more than a root grapple.
Seems the rock buckets are really optomized to drive through soil filtering out medium (>3 inches) sized rocks while leaving the dirt behind. I can easily see the use for such a device if the tractor has enough umph to push through the soil which depends on soil type and condition. I'd be concerned trying to use such a device with a tractor less than 30-35 hp in that way however. It would essentially require more force to move forward than an equivalent sized box blade with closely packed tines lowered. It looks like it has roughly triple the number of tines per unit of length as a standard box blade so pushing a 5ft rock bucket even in fairly loose soil might be the equivalent of trying to pull an 8 ft box blade with tines down. Of course if you just skimmed the surface with the rock bucket or were using it in sandy or well cultivated soil that would require less force to operate.
While the rock bucket would have clear advantages in picking up stones less than 9-10 inches or so in smallest dimension (which would just fall through the tines of a root grapple), I don't see that it has any advantage picking up bigger rocks. Any rock a root grapple can get it's jaws around can be curled up and moved just the way Jinman moved the big rock in his photos. Additionally, as the root grapple weighs less, you would have a better chance of actually lifting the rock rather than needing to drag or push it.
If I were cleaning up a construction site or trying to derock the surface of a cultivated field I'd go for one of these rock buckets in a flash. For general use however I'd think a root grapple or grapple bucket would be more versatile.
