Closeup of the rack mounted on my Trek 520 with no bags
The Jandd Extreme front rack is unique because you can mount panniers both low and high on it (as shown in the above pictures). This is handy for mixed touring, where most of the riding will be on paved roads, but some of it will occur offroad. On the paved roads you can use the rack mounted low, and when riding on trails you can mount the panniers high for improved clearance. It is also a very well built rack, and priced well ($55, compared to $40 for standard Blackburn front racks). The shelf on top is much larger then the shelf on the Blackburn MTN-F rack.
There are a couple of downsides to this rack. The first is that you have to slightly reconfigure Ortlieb panniers when moving them from the low-rider to high-rider position. This takes a few minutes and a 3mm allen key. The 2nd is that it didn't work with the mid-fork brazeons found on my Trek 520, so I had to use clamps for mounting. The mounting system with clamps works well, but it isn't as clean looking as using the brazeons. Finally, the Jandd Extreme front rack does weigh a somewhat more then normal low-rider racks.
June, 1999 Update: I recently machined two triangular pieces of metal which allow me to mount the rack using the mid-fork brazeons on my touring bike. It works quite well, and looks a lot nicer then using the clamp which came with the rack. To do this I used Aluminum bar stock bought at my local hardware store, and cut it into shape with a hack saw and Dremel-style rotary tool.