You could probably get the surly for $85 or so at bike island.
The Surly seems to have a much more flexible mounting system, and it is wider (good for mtb and 29er forks). The Jandd will not mount on my mtb fork without significant bending. It fits my cyclocross fork perfectly, and would work for a road bike fork that I have. I hear that the surly has a huge # of parts, so it may take a while to mount. Then again, many of my racks require a trip to the hardware store and some futzing around anyway.
15-20 pounds on the back should be kind of hard to notice when you get moving, so something seems odd here. If you put that weight on the top of the front rack, try to get it as close to the fork as possible.