It all depends on how hard you want to push the bike. I am not able to commit to a road bike because I deem it too fragile for my size and mostly for the wear and tear I put it through. My rides are much better when I know I can go off road whenever I want without worrying about tires, rims, or other parts of my machine breaking, snapping, cracking, whatever. Sure, she weighs a ton, but she is solid. Not to poo poo any road bike commuters out there, it truly is up to you and how you use your ride on your route.

You might look into a flat bar road bike. I have a Fuji Sagres (lower-end, but still rides nice) to which I added bar-end handlebars and fatter, more durable tires, and she can go off road for short spurts.