Rope training

Anthony DiLuglio over at Art of Strength utilizes the undulation technique with rope training (http://www.artofstrength.com/ropes/video.html) for metabolic conditioning. They advertise "Ropes Gone Wild" as one of the best means of entering that supra-aerobic zone (they don't call it supra-aerobic. I got that from Al Sears), training the core, and providing a means for low impact cardiovascular conditioning. I'll admit being tantalized by the idea of using the ropes, but due to the priceyness have yet to do so. What is SSL's take on this training modality? It seems to fall outside of the traditional praxis of cardio conditioning and, at least to me, is akin to rowing as a superior form of low impact conditioning.

Thanks,

J. Richardson, CFT