SootyBob, I have a Bush Hog CS100P (you can just see it behind my Ford Jubilee in the PHOTOS forum, under the title, "So Many Tractors..."). It can chip up to 5" diameter, but works best on 3" and below. Anything bigger, I call it "firewood." The shredder portion is a beast. It can take up to 1-1/4 diameter and the drum shredder inhales it like teenage boys at the dinner table. I also have the blower attachment on the output and my suggestion would be to get this too. It really spits out chips and limbs. I have a three-wheel dump cart that I put sideboards on for the "catcher". The chips/shreds come out with such force that my four-foot solid sideboards won't even contain all the chips. I have a lot of red cedar trees and this jewel is just the ticket for making the nicest smelling cedar mulch you could ever want.
Oh yes, that price thing. I bought mine used. My New Holland dealer sells consignment equip and had it on his lot. I'm sure that new this one sold for about $2,400 without the blower. My guess is that the blower is another $350-$400. I got the whole rig for $2,200 and it was so new, even the paint wasn't worn off the drum cutter. The owner used it a couple of times and was frightened when he found himself getting too close to the cutter blades. As a prudent move, he decided to sell the
chipper/shredder before he came up minus fingers. Again, safety is a M-U-S-T with one of these things. If you are accident prone, forget it.
My Ford Jubilee is about 32hp, but it operates the C/S without much difficulty. I think your Kubota could handle one this size since Bush Hog sells one the same size with a 18hp engine as a dedicated unit. There are several "manufacturers" (another is Bearcat) who sell these things, but they all look similar and it leads me to believe they are OEM'd by someone who paints them different colors and wholesales them to Bush Hog, etc.
Good luck with your search. Like me, it will probably be a tradeoff between what you want and what you can afford.
JimI