I started commuting this summer with a brand new hybrid and have become addicted to commuting by bike. This w-end I converted my old MTB into another commuter for bad weather days. I did a test run , and enjoyed the more aggressive, aerodynamic sitting position and the wide tires that smash through road debris, provide more stability on the gravelly parts and allow me to take short cuts over rough unpaved sections. It does have much wider tires than the hybrid, but I switched from knobbies to smooth tires, and I don't think I'll lose much speed (if any).

I had assumed a MTB was going to be much inferior to a hybrid or road bike for my commute and was genuinely surprised by how much I liked the MTB's features. I guess it won't be long 'til I get a road bike.LOL.