Yes, I know EA introduced a rake or clamshell type grapple earlier this year. The notable thing about it is the weight. Although in general clamshell style grapples are really only useful for collecting brush, the weight does factor in for subcompacts and compacts with less than 1000lb lift capacity.
The MAJOR downside of a clamshell is that any stick or log that jambs in the hinge will stop the grapple from closing further. If you just need to pick up a single log at a time that is not a big deal but if you are trying to pick up a pile of logs or branches or a combination of types of debris, then the hinge jam will severely limit the size of the load you can secure. Same story with 4n1 buckets when used as grapples.
If you consider two piles of debris and load one with a standard "L" grapple and the other with a clamshell you'll see what I mean. The standard grapple pushes under and into the load and only when the grapple is full do you close the top jaw to hold the load in place. The load is actually resting on the fixed bottom tines so gravity is doing most of the work and the upper jaw simply keeps the load from falling out forwards. With a clamshell you load about the same way but as the bottom tines are very short, the load is held in place not by gravity but by compression of the upper jaw. All fine and dandy unless there is a log or branch in the debris pile that sticks out beyond the hinge. If it does, then NOTHING below that branch/log will be secured and will fall out of the clamshell as soon as you lift it. Been there, done that (with a 4n1).
Clamshells may or may not be better for simply collecting soft bramble type brush but they are definitely not as good as a standard grapple for collecting mixed material of different lengths. Main issue as described is that gravity is your friend with a standard grapple and is your enemy with a clamshell.
I'd get a clamshell if I really had a weak loader (think Kubota BX) but if my loader could lift close to or more than 1000lbs then the standard is more flexible.