As far as the 'couch' analogy is concerned, I've heard it before/still don't get it! I realize all this is partially subjective, but: what is necessarily 'couch-like' about a mtb any more than any other bike type? Take a good, sub-25 lb. x-country hardtail, set it up with a proper 'xc race' riding position (which apart from the drops mimics a trad. road position), use a light xc wheelset w/ 1.5 or so slicks/semi-slicks -- how a couch? Such a bike will allow one to snap away from traffic lights etc. extremely quickly, move along over distance at a very good pace, go off-road at will, avoid obstacles, and so on. Or, set it up as a 'couch' -- as you will! But surely one could do the same with a road-based bike?? Raise the bars, slap on a 'comfort seat' and some 35 or 38 road tires and you have a nice comfy but sluggish 'couch' -- whatever!