I agree with tassinari that it's all about compramise one the tire choice for your situation. I recently switched from a "commuter" bike to a road/touring bike, and both have the exact same tires - Vitorini Randonuer 32mm. The performance on gravel with these two bikes is identical really, but I have to admit that I only have a couple of short 40 yard dashes across that type of surface.
On a side note, my commute is 10 miles - I couldn't imagine doing a full 30 miles one way, every day, on my previous commuter bike. My lower back and hands would suffer at that distance without the ability to vary my riding and hand positions like I can on my new bike. I would experiement with tires on your existing road bike.