Yeah, DCS, like so many have said...."what will you use it for?"
Personally, for super tough stuff I would dump the J.D. and move on to a Dale Phillips or some of the over-built types. My dad bought one of these and it's like a tank. The John Deere shredders have never impressed me for the prices they ask, but it could just be I've never seen the right one.
King Kutter and Howse seem to fall on the lower end in terms of price, and, I've looked them both over pretty well. Either will do absolutely fine for general use and the occasional rough spot. The base 5' KK is slightly heavier than the comparable Howse, but the Howse seems to have a better milled pan/blade set-up. Half a dozen one hand, six in the other. I wound up buying a Howse 5' ultimatley because Northern Tool sold the bolt on chain guard group at a convenient price. The KK's will need a customer designed and home built guard of your own making because the deck lip is different and, well, I wasn't able to find anyone who sold it.
For a 100% price difference, personally I'd buy the KK and go about my business. If you tear it up, then you have paid a small price to know what you need and it's time to step up the big boys.....Bush Hog, Woods, etc. If not, then youv'e got a cheap shredder that will last for years with routine maintenance....