By closed bottom, I assume you are describing a standard bucket with a claw on top?? If so, I think this root grapple is better for most things I use it for, such as collecting and carrying chainsaw debris, uprooting saplings, trees up to 6" diameter, grabbing large rocks, and even grabbing implements (such as a disc or plow) for moving or loading. Last night we were in a hurry and needed to load a disc on a trailer. We simply grabbed it with the grapple and picked it up and placed it on the trailer. My loader has about a 2500 lb. capacity, and I expect the grapple I have and the one you show weighs 600 or 700 lbs. I really never have any problem with exceding this limit unless I try to pick up a rock as big as the house, something I should know better to even try. Debris or logs are never an issue.
What these grapples excel at is clearing land, especially some grown up in small trees and undergrowth. Or for big trees, they make quick work out of hauling off the cut up debris and sectioned logs. I don't see a closed bottom bucket being able to do this as well.
I agree with Island Tractors's philosophy of a narrower one (48") being ideal, but for the price of the one you are looking at, I don't think I would spend another $800 to get a narrower one. The only thing a narrower one would do better (in my opinion) is focused digging or uprooting of a single larger tree.