Hi Rat...
Wr Long does make larger ones...next size up is the UJ1. It has more capacity, a little beefier and heavier. The UJ2 is perfect for my size tractor. It is heavy duty and stout enough for everything I have used it for, (moving concrete, etc). I am satisified with it. They also can add a spill guard to the bucket top/back for more capacity, which would be good for lighter material such as chips, manure, etc. I also got the WR Long electric diverter valve. More money, but I recommend it. Since it would be plumbed, having a grapple also would make you pretty diversified.
When I get back to the house, I will look on my sales receipt and PM you. It's good to go to several dealers and look at their aftermarket 4in1's to compare. I believe Kubota now has a 4in1 offered as an option. You may want to check that out. I do not know who makes it for them, or if they are making them themselves. One of the members here...(Builder, I believe), was looking at them. Maybe ask him, too. I am biased and like the WR Longs, though. Many people around here have them, also. Maybe Nelson Long can answer a question or two, since he is on our boards.
PS...If you are just doing brush, all you need is the grapple, like KennyD said...