I have long admired and desired the Bikes At Work trailer, I liked the idea that it could be adjusted for length. The 300 pound capacity didn't hurt anything, either.
I am not familiar with the trailer --hpm-- mentioned in post 4 above, however, it sounds shiny, not having to worry about the weight of the load. The weight of the load issue is my biggest concern with my Burley--it is only rated for 100 pounds.

I also like this trailer especially for touring/camping. You have shelter and you can still carry gear and supplies.

Having said that, a trailer with a 300 pound capacity, designed to play well with an Xtracycle/Big Dummy would merit some thought, when I am considering throwing some cashy money for a new trailer.

If I win the Lottery, this trailer would be on my "buy" list: