The only difference between a cyclocross bike and a rigid mtb, is primarily the width of the tire used. Since, the width of a cyclocross tire is usually limited to a 35mm width, it would prove to be more "efficient" on paved roads as opposed to trails. However, once we move over to the wooded and rooted trails, the cyclocross bikes drops precipitously in efficiency and loses its level of versatility to the MTB. Whereas the MTB would suffer on pavement, the cyclocross bike would suffer most on extremely difficult terrain.

Therefore, it comes down to the type of terrain within a given area. Hell, on nothing but paved roads, a simple road bike would be ideal, but not versatile. Versatility is owned by that bike which can fill the most roles with the greatest amount of efficiency. The barometer for road efficiency will always be the given terrain.

So, in a way you could be right. However, in the total absence of pavement, you are so very wrong!

- Slim