By "less pitch," do you mean "less space between tooth centrelines" or "less teeth per unit length?" The two are opposites.
If you mean fewer teeth per unit length (teeth per inch, for instance,) then it increases power handling due to the greater material in each tooth and the greater cross-section of each tooth, which makes the teeth stronger. Granted, there are more variables involved than that (a gear that is thicker will have more lateral distance than a thinner one, and will also therefore handle more torque without shearing off teeth...) but that's the gist of it.
If you're talking the other way - less space between centrelines - then you'll end up with a gear that actually handles LESS power, assuming the same material used as the other "two" (the normal one, and the one with fewer teeth per inch.) Reducing the distance between centrelines actually will increase the number of teeth per unit length, and reduce the material in each tooth.
5-90