Another factor I am going to mention here (before Vance does it for me :-))
is the effect of the power to weight ratio of the airplane. Most 2 place or
single place experimental airplanes are in the category of a high power to weight 
ratio airplane. In that case a constant speed prop becomes less important as
the airplane will take off fine from most low altitude airports.
Even if the prop is stalled it will still generate enough thrust to accelerate
the airplane to takeoff speed well before it runs out of runway.

In the case of the four place KIS Cruiser and some of the larger and heavier
designs such as amphibians with two rotor NA engines this is more of a factor.
 
Paul Lamar
 
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