I never found the HD800 light on bass. In fact, when I auditions many cans before buying a pair, the really notable thing was how incredibly low and clear the 800 managed to get without sounding dark. I had always assumed that the 800S was to address the other end of the scale since so many people are fans of modding (or ruining depending on how you see it) their 800 with thick felt added to the inner fabric grille.
One of the thing I was impressed the most was its clean and fast, almost SL2 like bass delivery. Seamless from top to bottom, it possessed the nimbleness of electrostats but with firm transient attacks of dynamic transducers.