Here's my review on the 97D
TLDR; It's a more stable HD, but there's no flex. It's like an Ultra Tour/Head ProTour. I recommend stringing the frame at the same tension because the frame still provides plenty of control and not much more power to me.
I thought this would be a more powerful frame, but I was mistaken. I usually string my 97HD at 48lbs, but with the 97D I had Champs Choice at 52lbs. I thought with the slightly thicker beam and increase of stiffness and swing weight I would need to up the tension. I could not get a FH in for the life of me.
Don't get me wrong, the frame is solid, but it doesn't have that flex that I like with the HD. You'd think it would still have that flex with the lengthened throat, but it doesn't. After putting on 4 strips of lead tape (1/4 width 2 inch length) at 2 and 10 o'clock it was night and day. From being unable to hit over the net to swinging away with plenty of spin, pace, and control.
Before the lead tape serves and volleys were pin point for me in precision, feel, and stability. Groundstrokes were lack luster, but I think if I strung it at either 48lbs or 50lbs it would be different.
Would I say this is an upgrade of the former 97HD? Imo, not at all. The 97HD reminds me a bit of the iPrestige, but the 97D reminds me of an Ultra Tour or the original Head Pro Tour. If you like the flex of the frame, stick with the HD. You can add a bit of lead from either 9-11 o'clock and 1-3 o'clock since some ppl complain about the stability.
If you like what you've read then maybe the 97D is for you, but for me I'm glad I have 7 of the 97HD frames XD
I play at a 4.5 level with an all around game and tend to hit a flat heavy ball