Not surprising. Just wanted to make the point of 3U - all my rackets are 3U too, and I'm not a professional, nor do I train even once a week hehe. I had both 3U and 4U Z-Force rackets once, and I definitely preferred the 3U.
I've used a whole spectrum of victor rackets and am comfortable with most of them. Right now depending on my mood I rotate between a BS12 KRP, JS 8ST KRP, BS12N and MX80.
I have gone with the 3U TK9000 before but gave it up due to needing cash. It was playable but not the most excellent on level doubles for me. It was an excellent candidate for mixed doubles though. But I rather liked the increased average power but want more maneuverability for level doubles.
I used to use the JJS as a go to in rotation 3U naturally I'll admit the TK9000 has a real solid frame but I've never personally owned a 4U for any racket before so I have no idea how survivable they are.
Sadly in Europe we do not have the choice of weight compared to other countries/continents.
There are some rackets I'd dearly like to try in 3U such as Jetspeed 8's, TK 7000S to get a better feel of the difference. However, tolerances being what they are there is always the danger the difference between 3U and 4U could be a knife-edge of 1lb or 8-9 lbs. I know i can add Powerizer and test but sometimes there is just something extra in the entire racket rather than one particular area like the head.