I have the 2-wheeled Quik-Pak trailer and have also toured with panniers. I don't have a Bob, but have toured with folks that did. The BOB was originally designed for off-road riding down single track trails. For that purpose its design makes sense. However, for road riding I find that my 2-wheeled trailer is much more convient then the Bob. It places substanailly less weight on the bike, doesn't impact the handling/balance, is substanially easier to attach/detach, stays upright when detached, and is easy to wheel around camp or hotel. The Quik-Pak is also offset, so riding close to the edge of the road is possible. You do still have 3 wheel tracks, so if an object appears in the road, your chances of hitting it is more likely. Also, at least for the Quik-Pak is that it uses 20in wheels, so tires/tubes are readily available, even at Wal-Mart.

Brian