It's not so much the bike, as it is the motor ;-)

I use a 56cm, 700C LHT as my primary ride. Commuting, utility riding, group rides, out cruising with my sweetie, whatever. Even played polo with it a time or two. The LHT is heavier (mine, with racks, weighs a little less than 34 pounds), has a little longer wheel base, and wider tires than does my 18-lb carbon fibre road bike. So I'm not as speedy-fast on it for the same level of effort as I would be on my carbon bike... but I've found over the past several thousand miles with it that I can be as fast as I need to be, or want to be.

Your mileage (and Mph) may differ... ;-)