I just bought a TSi3 with the tour AD XC-6 and I am very impressed with this shaft. I have a very high spin rate and had been previously using a TS4 with a tensei white 70 gram shaft extra stiff shaft, and my spin rate was still on the high side. This new driver I am able to hit the ball in a much tighter window with optimal launch and spin numbers. It was worth the extra $200 for me.

And how do they work with different flexes and different weight?

Bought mine with an AD IZ5 Reg shaft
I will use it for the first time on Wednesday when English courses re-open
So excited!!!

I recently was fitted for the new TSi3 driver. During the fitting I used my Graphite Design AD DI6 shaft in the TSi3 head. It worked beautifully. I have since ordered the TSi3 Driver and TSi2 3 Wood with Graphite Design AD Di Shafts.

Last week my 18 year old son bought the new Tsi3 driver with HZDUS Black stiff shaft. In the simulator he was driving it 320 yards. His longest drive was 348. He tried going to x-stiff but the ball flight went consistently left and was very clearly not the right shaft. Yesterday we went to play and on the second hole the shaft broke. It didn't break at the hosel it broke half way up the shaft. He literally only had the club for 3 days and I've never seen a shaft break where it did. It didn't break clean in half but was held together by the graphite fibers.

Anyone have thoughts on why the shaft would fail like this?

Thanks

If they made 100,000 shafts, and the defect rate was 0.001, that would still be 100 shafts. So it may be one of those few shafts. Titleist will make it right. At that club head speed, you might want the equipment specialists at Titleist to f/u to see if they would still recommend the HZDUS.