You will also get better gas mileage, less engine wear, and less vibration because the engine's RPM's will be lower during high speed cruising.

Hmm, same doubt here   Problem is that:

1) I bought my 98 Savage with 10k miles on it, 15 years old original belt.
2) Within 3k miles the belt was gone - first a puncture and than a 1" tear
3) Ok, there's some gravel on my street but I ride very slowly on it.

I'm not exactly happy with the idea of changing the belt frequently.
Is the belt/pulley really a system that requires clean roads?