I installed a Velo Orange Portuer rack on my Kogswell in the summer, and rode it for about 4 months. The VO rack works very well, and looks excellent. The only complaint I have is that by attaching to the fork drop-out, it stiffens up the lower front end of the bike, and makes handling slightly more awkward, especially on fast winding descents. This is really being nitpicking. I also lament the fact that I can't use the fork crown braze-ons on the Kogswell fork intended for porteur racks.
Miles Whitmore of Roseland Cycles posted on the Kogswell yahoo group that he had enough tubings to make 5 more porteur racks designed to go on P/R's fork, and Roseland might not make these racks in the future. I emailed him to reserve a 650b version right the way. 10 days later, I met Miles in Berkeley not too far from my apartment--it turns out that Miles and his partner is moving Roseland down to Berkeley from Santa Rosa, and current works out of a garage a few blocks away--and grabbed the rack from him.
porteur rack bag that Swift Industries makes on the rack.
I have ridden around time to buy groceries, etc. on the bike, and it feels not much different than when I was using the VO rack. However, on several hilly workouts in the Berkeley Hills, the restored suppleness in the front end on fast descent is certainly noticeable--the bike feels spriter, more responsive, and I feel more confident taking a turn at high-speed.