My Kogswell is designed to carry heavy front loads, but didn't do so well with loads both front and rear. After a lot of adjustments failed to correct the problem, I thought adding an Xtracycle might smooth things out. So far it seems to be working.
The magic of the Xtracycle seems to have cured the front end wobble on this machine. This load -- a week's worth of vegetables, a gallon of milk, and various and sundry bits of clothing unneeded or unworn -- is my largest regular cargo. Once a week we make the 14-mi round trip to our CSA pickup and haul home our bounty. In the fall it's much bigger. But it's the milk that usually tips the scales. With the Xtracycle I barely felt like I was carrying anything. I have yet to try it out with a full camping load but I have high hopes at this point.
Installing the Xtracycle unit on this bicycle was relatively uneventful. The Kogswell uses 650B wheels, which are slightly larger than 26" wheels (650B=584mm ø, 26"=559mm ø). I used a 26" Xtracycle and a V-brake, and with a little filing of the brake arm slots, the brake shoes met the rim just fine. I think I voided several warranties in the process, but if I run into any difficulty I reckon I can switch to a 26" wheel and a big fat tire on the rear.