to answer your question, i do like the pros of the constant speed prop.
1. better climb
2.better speed reduction
3. fixes the aft cg problem with a backseater
4. since its metal it polished up real nice.
but the added cost, weight, and maintenance are not really worth it in my option. If I were to do it again i would go with a wood or composite fixed. possibly one of the ground adjustable props. I have heard great thinks about the catto props.
at the airport that I built mine at my friend has a 160 hp rv-4 with a fixed pitch wood prop. mine is 360 c/s. I could get off the ground a lot faster and climb faster but i only had a couple of MPH on him at top end.
bob burns