I have a Twist with a Saito .72. Started using a 13 x 6 Master Airscrew prop. The plane flew great. I then tried a APC 13 x 4W. The plane did have a improvement with the APC, so I tested it by using a digital fish scale and tied one end to a post, the other end to the tail of the Twist. Here is what I recorded:

13 x 6 Master airscrew = 6.7lbs of thrust
13 x 4W APC = 7.5lbs of thrust.

I think you can guess what prop I am using

Larry