Just to clear one thing up. The Airmaster is not an IFA prop. It is a fully constant speed prop and that is why it's performance is way above everything else.

The IVO is an IFA and there is a constant speed controller unit for it but I haven't heard great things. An IFA is better than a ground adjustable for sure but if you are looking for the ultimate performance, the Airmaster is head and shoulders above the IVO

This is an excerpt from a message WarEagle sent me regarding his Airmaster:

"But I fly with a four other Kitfoxes with 912s and the same CS prop that I have and many times we meet other kitfoxes that fly with us with the IVO IFA on their 912's equipped fox. The IVO's can take off first then the the planes with the same CS prop as mine take off and the IVO's get caught up to and then passed in less than 20 minutes off the deck. It's a pretty cool sight to watch because the IVO guys can't believe what they are seeing. While we don't have hard numbers to give you I would guess that these CS equipped planes are seeing at least 4-6 mph (over the IVO guys) on cruise and probably 100 - 150 fpm better on climb out. "