I recently purchased an 8.5* D4 driver with the 125MSI 60TX Rogue shaft and have hit it in an indoor simulator as its below freezing here in NY. For comparison, I played a 9.5* 915D2 all year in 2015 with a UST Elements Chrome 6f5t. The D4 launched about 1* lower than the D2 with 400rpms less spin. What I noticed more was the D4 was producing ball speeds in the 172-173mph range while the highest I saw with the D2 was 170. I'm sure the D2 is much more forgiving, but I'm anxious to get this out on the course for some real world results.

Mike, I have the exact same question. I came to the forum to see if I could get some insight.

Travis K - Thanks for the info. Keep it coming once you get to play it.

Courtland - I have been scouring the web too for any kind of review and have come up short. I game my 910 D3 with the Diamana 'ahina x flex 70 really well but its going on 6 years old now so it may be time for an upgrade. If you come across any info or data, let me know.

I changed from the 910D3 to a 915D2 and it has improved my driving accuracy. I realize you asked about the D4, but thought I would throw that info in for measure. That larger sweet spot does make a big difference. Lost maybe five yard in distance but the accuracy more that out weighted that loss of yardage. Much easier to make birdies from the middle of the fairways. The key is getting fitted with the right shaft. Try both heads and see which works best at the fitting.

Everybody thinks the D4 feels so different when the only difference that ive seen on GC2 was spin. It looks the same, it feels the same, it has a similar launch, just reduced spin.