Going by some recent comments by Paul Stewart (something along the lines of "3U very head heavy rackets don't interest me", perhaps it's not accurate to compare a 3U head heavy racket with a 4U head heavy racket. Perhaps Paul would find the 4U Z-Force II a better defensive racket than the 4U TK9000.
By the way Paul, it's nice to know that there is good evidence of some pros who don't have customised rackets - you mentioned in your recent blog post that all the rackets you strung in the recent All England were standard models. I think this needs to be stickied somewhere in this forum hehe. There's so much mis-information about pros having customised rackets etc. I wouldn't be surprised if none of them did, and even those signature rackets are made only slightly differently so that the brand can make more money (while the player etc still performs the same).
To answer some of the comments and questions above...
Sadly we will not have 4U ZFII in UK so I cannot compare as you would like. In UK we do not have the same choices you have in respect of weight and grip size. We only have one version.
I believe Victor makes world class rackets that are as good as Yonex, occasionally better. I have asked a number of players to test ZFII and TK9000. 80% chose TK9000 as a better racket. None of the players had many positive views on ZFII. Many are Yonex users.
I was surprised at All Englands to find the players using standard models rather than custom rackets. We only saw one KRP racket all week. Perhaps the likes of LCW has custom rackets but we did not see those rackets as Victor stringers are not allowed in the arena - which we were extremely happy about.