I use the Kimpex on my Rincon and like it a lot. I also have one on my Grizzly.
My only complaint is that the Rincon's rear rack isn't very deep, so the box hangs off the back 4-5". I attach the box using U-bolts so it stays in place, and I also added my own weathestripping to keep the dust and moisture out.
This is the only box I've found with metal, locking latches. You can even buy replacement latches ($10 each) if they happen to break. It takes a lot to break them. The one on the Rincon is the one that came off of my Arctic Cat 400, which I rolled down a very steep hill about a year ago. The box was flattened out and the latches ripped off. Rather than throw it away, I tossed it in the back yard and ignored it for a few months.
Then one day I was out there and about to toss it, when I noticed that it had returned it its original shape. Wow. So I called up Kimpex, got the part numbers, and ordered new latches from the dealer I got it from (ATV Direct). A few weeks later, the latches arrived. I removed the remains of the old latches and attached the new ones with nuts and bolts, and it's been working great ever since.
The only box that could be a better fit is a really nice heavy duty box from Polaris. It's not as deep, but it's an inch taller. It has rubber latches that aren't locking, but it's a double-wall box with a really nice weather seal. It only says Polaris on top so it wouldn't be so obvious to bystanders.
I have a Plano Box from Bass Pro Shops ($79...mention internet price). You can see it on my Rincon in the pictures at my profile.
The price was right and it seems pretty well designed and made. I modified it with metal hinge and mounted it with U-bolts so it hangs out about 8" to make room for my dog. I also added an extension to the rear rack to support it.
It doesn't seem as big as the Kimpex but it is adequate for my needs....fits the Rincon very nicely. When the fuel and water packs are full I can put the Tamarack box on top of the Plano to balance the load.. I've never seem a Kimpex in the flesh so can't give you pros and cons.
If you are interested, you might find them offered in your area or contact Bass Pro Shops to ship one. Hope this helps.
I would just like to add that I have the exact same box as Rob and it is great! Put 3 soft sided coolers in there from Wal Mart. 2 for beer and 1 for dry storage for extra clothes, etc just incase I get wet. I have had it since I have had my bike for the most part and it is great. I also added my own weather stripping from AutoZone right when I bought it (I don't know if it needed it or not, but I figured it wouldn't hurt).
Highly reccomend it! Bought mine for around $130 or so, but worth it.
I received my Kimpex box yesterday and hope to mount it this weekend. RobG mentioned using U-bolts. Did you (or others) put any foam tubing or rubber hose on the rack itself prior to installation to help hold the box in place (and offer a little cushioning)? Also, any info on the U-bolts? Size?
I found a Contico box at Wal-Mart for under $20.....bought four 1" u-bolts at Lowe's to hold it to my rear racks. The box works fine. It's as good as the $100 plus boxes. And it fits well on the back of my Rincon. For $20 you can't go wrong.