Hi hillmower,
I bought a KingKutter XB48 bush hog for my
B7610. Only got it last fall and can't really say how good it is. It does seem quite stout, however, and the
B7610 has enough lift to easily get it off the ground. Being designed for the BX size tractor, the cutter's 3pt. hitch dimensions fit the
B7610 well.
One thing I noticed is that the blades are rather stubby with only the outer 6 or 7 inches sharpened. That and the manual mentions prominently that the hog should only be run at 540 PTO RPM. Apparently the cutter uses the same gearbox as KK's larger cutters and the short blades with resultant low tip speed cause cutting efficiency to fall off quickly at lower RPMs.
I cut around trees a lot so Low Range is the rule. I'm looking for downed branches, limbs, marker stakes, etc. and watching where the cutter swings as I S-turn around trees so cutting in High is not an option.
If you're cutting easy stuff in the open, a 5 footer might be worth looking at. Just make sure it matches the somewhat reduced dimensions of the
B7610 3pt. hitch...and that it doesn't pull the front wheels of the ground when you lift it. You probably could leave the FEL on the tractor as a counterweight, but it will make the rig less maneuverable.
BTW, the Implement Limitations section of the Kubota manual (pg. 5) recommends a max. Rotary Cutter size of 48" with a max weight of 400lbs. That would be your best guide in determining what's suitable.
Bob