Usually a shorter prop is associated with higher rpm and more pitch so more speed, less pull. IVO at one point in time did not recommend their props on a 3.0 gearbox because of the vibrations the 3.0 gearbox setup. That said I ran a 3 blade ultralight 68inch for 400hrs and never a problem. It was always smooth easy to adjust and fit the airplane well. I tried a warp drive and found the two blade very difficult to adjust and get smooth. I finally worked on it with a friend, got it smooth and it is now on his Kitfox. Still not as smooth as an IVO. The warp was a 2 blade 70inch.
I know nothing about Luga and Bolly so I can not offer an opinion.
I think for a Kitfox you want to stay with a 68 to 72 inch prop two or three blade. I am not sure why warp suggested a four blade 64inch Usually they are pretty good at getting the right prop and plane combination.
One other thing to remember is Warp and IVO are next door so to speak and getting parts is always easy.
Good Luck