Keep in mind that a constant speed prop gives you 2700 RPM on take off, this gives you all the 180hp (in theory) as opposed to the what ever HP at a given RPM a fixed pitch prop gives you. As for speed, its not about speed but efficiency. In Bill's case where he gained 7 MPH in cruise that could equate to a lower gallons per hour fuel burn or if he kept the power up 7 more miles per hour at the same fuel burn, either way, a big miles per gallon increase over his fixed pitch prop.
If you are burning less gas that means you carry less gas for your mission or you extend your range and maybe not needing to carry cans. Also with a constant speed prop, you are able to come up with various power settings that fit your mission. I have been amazed with some of the power setting/fuel flow/MPG combinations I have been able to achieve. Case in point, when I fly my 0-360 powered Husky just out putting around, I fly at an "over square" power setting, say 1,950 RPM and 22 inches of mp. At these power settings I am doing 115 statute miles per hour at 5.5 to 6.0 gallons per hour. That is pretty darn good speed/fuel flow result that only a constant speed prop can give you. If I need to get somewhere quicker I can pus it up and still obtain great miles per gallon results.
Now it does matter if it is a Scout, Husky or Super Cub, if you can vary your cruise power settings like this and get a full 2,700 RPM on take off then I think it is well worth it. MT Ultra or Trailblazer, either prop is great, having flown both I prefer the MT, I think its a bit smoother and performs a tad bit better but that is just me, John may disagree.
Kurt