Sorry to bring this topic up and live again. I had read this topic some weeks ago because myself was wondering between ZF 4U and Z-Speed 3U.
My friends told me ZF was extra stiff, very very hard to use (especially to me since I don't have strong arm and wrist) so I listened to them and get the Z-Speed 3U. First 2 days was total disaster, but after that I get along pretty well with the racket and quite satisfy with it, the fast swinging helps my defence and backhand a lot compare to Arcsaber11. I play single for most of the time, I don't like double. Lots of people told me Arc11 is easier to play than Z-Speed, but to me it is completely the opposite, I had to let my Arc11 go after a month of using it.
However, I'm so in love with the color of Z-Force normal version (not the LTD version) since the day it came out so I always want to have one (ok, I love the color, not because it's being used by LCW, I don't really care about pro's racket).
So how is the extra-stiff of Z-Force compare to stiff of Z-Speed? Is it noticeable?