here's a generality for you:
take a look at who is riding the heavy bikes: are they the people that cruise down to the minimart to buy the newspapers or are they the ones doing 25-50 mile rides with the wind in their hair? (under the helmet i mean )
Sign up for a distance ride and see how many cruiser riders are on it.

There must be something to this light bike stuff or so many avid cyclists wouldn't be riding them.