(Update 10/2/2014: SKS have updated their fender line and the Chromoplastic fenders and Longboard fenders have been combined and are now called SKS Chromoplastic Longboards)
The SKS Longboard fenders are in at the Bike Touring News Store. I have been anxious to see how long these really are. So I did a side by side comparison with the Honjo alloy fenders and the Planet Bike Cascadia fenders.
The rear fenders are about equal in length, but with an aftermarket mudflap the Honjo fender would provide the most coverage, maybe not as important as front fender coverage- except maybe for whoever is behind you!
Arguably, the coverage provided by the front fenders is the most important because the farther the fender comes down on the trailing side the less spray onto the rider’s feet. And as we can see, there is quite a bit of difference in the coverage of these three front fenders.
In the above photo of front fenders the fenders are positioned according to the point where they would attach to the bicycle fork, and you can see that the Longboard fenders are the longest providing more coverage in the front as well as in the rear than the other two. To be fair, with an aftermarket mud flap the Honjo fender would provide equal coverage.