I have to weigh in here with my own comments. I was on that ride with C2C4C / Evan yesterday (that's my white DR parked next to his yellow one at the mandatory Starbucks after-ride shaken-green-tea and milk-chocolate covered graham crackers...but I digress).
I was absolutely amazed at the performance of the trailer. We rode some gentle single track where you would expect it to handle well, but then we got into some very tough, rutted trail where ANY riding was tricky and difficult. Eventually we ended up where there was no trail at all, forging through heavy brush and some difficult ditches. All along the trailer not only followed dutifully without a complaint but did so without causing any challenge at all that I could see. I rode point some, and the trailer didn't slow him down at all. When Evan rode point it was almost mesmerizing to watch that thing behind his bike.
The only issue at all is when you go through a really steep ditch, the trailer angle (up/down) is such that the pivot hits the fender/license plate (as has already been mentioned) because the length of the "arms" or "tongue" is the same as the distance from the axle to the fender/license plate. But these were short steep ditches that we almost had no business crossing, trailer or no trailer.
My DR is just for use around town - I have bigger bikes for bigger trips - but if I needed to haul anything with me I'd buy one of these things in a heartbeat.
Well done, MrBracket.