Bohniong's website gives a good explanation between the longer and shorter vanes. While Blazers are shorter as bruce says they are a little taller. Anotehr factor is that they are stiffer than a nrmal plastic vane. Therfore, you can get the same control with a blazer that you get with a longer vane.

Long vanes where developed as a trade off to feathers. However, being heavier and not as stiff they're not perfect. Feathers are better but are easily damaged. Manufactures also make plastic vanes that are cut like feathers. Still not the same. They are stiffer than regular long plastiv but still heavier and brittle.

Not until the Blazer, or other short vane, have manufacturers been able to get feather like control, and weight, out of a plastic package.

If you still want to use Blazers you can use wraps to increase weight without resorting back to long vanes.