So I finally received my demos of the 3 various iterations of the VCore Pro 97 (310, 330, and HD), and I was able to hit with all 3 tonight. Here are my thoughts and experience so far with the frames.
The 3 frames all feel very similar- you can definitely tell they are part of the same "family". Differences between the frames are fairly minor, and are more a product of the weight differences between the frames than anything else in my opinion. If I had to describe this family of racquets, words such as comfortable, stable, consistent, and easy to swing all come to my mind. I would characterize these frames as low powered and control frames, but do not let this deceive you- these frames can all hit the ball with pace and spin- they will put out what you put into them, but they aren't going to give you a lot of free, easy power like you might get from a Babolat frame. The three VCore Pro frames I had were all strung up with a multifilament. I put an overgrip on each and a babolat vibration dampener and weighed each one. The weight for the VCore Pro 97 (310) was 334 grams, the HD was 344 grams, and the Vcore Pro 97 (330) was 354 grams. I was not able to balance them but they all felt similarly balanced and swung very similar. Specific thoughts on each frame are below.
VCore Pro 97 (330)
I probably have the least to say about this racquet, but this should not be taken as knock on the frame. This racquet is absolutely solid. It's a tank. The extra weight just provides a noticeable level of stability even above the other 2 frames. The frame did not feel stiff, but I did feel like it was a smidgen stiffer than the 310 model (which is consistent with the stiffness ratings that TW posted of the 330 being slightly stiffer). Despite the weight, I felt like the frame did swing easily. However, I just was not able to generate the same racquet head speed that I wanted and experienced with the other two frames. This is not a knock on the frame, though, as I'm just not enough of a man to yield this beast. For those players who can swing it, I have no doubt it would reward them.
VCore Pro 97 (310)
This frame felt easy to swing, and I could generate a bit of extra racquet head speed. The frame is solid, but does seem to be missing a little something. I added about 2 grams of lead at 10 and 2 o'clock, and that seemed to help provide the frame just a little extra oomph that I was missing. This racquet is obviously the most maneuverable of the 3 frames due to its lower weight, but I still felt the frame hit solid on all strokes, including volleys. I actually liked serving with this frame a little bit better than the other 2 frames, but that is probably more a result of the racquet head speed I was able to generate with this frame versus the other two
Vcore Pro 97 HD (18x20)
This probably turned out to be my favorite frame of the 3. The weight was less than the 330 model, which was just too much for me. The extra weight of it versus the 310 gave it that much more of a solid feel, so much so that if I switched back to the 310 I would instantly miss that extra weight of the HD. Regarding the string pattern, I did not feel like it was an overly dense string pattern. In fact, if you hold the 16x19 and the 18x20 to each other, the spacing seems extremely similar. However, I did notice the 18x20 gave me a more controlled launch angle and provided even more consistency. I have a very steep forehand swing path, and I am prone to really launching some forehands with too high of a launch angle off the strings. Thus, I actually really appreciated the 18x20 string pattern, as it helped to mitigate that issue for me on the forehand side. I think the 310 frame is probably a little bit easier to generate spin with, but I would not say that spin is hard to come by on this frame (or any of the 3 for that matter). The HD feels only slightly less stiff than the 310 and 330. In fact, I would never have believed someone if they had told me the RA stiffness rating on this racquet was a 59 (I would have thought is was like a 62 or 63). None of the 3 frames play stiff or harsh, but there were shots from time to time where I did feel the extra flex in the HD frame versus the other two.
Other random thoughts
I think all three of these frames can hit spin, but I think they really excel on flat hit balls (not sure why exactly). I really loved hitting a flatter forehand up the line with this frame. Flatter type serves seemed a bit easier to hit as well (but certainly no problems hitting topspin or slice serves with the frame). Groundstroke slice shots were smooth and buttery as well.
I am really curious to see how these frames might play with my normal string set up. I sometimes use a hybrid of poly mains and synthetic gut crosses, but I have been using natural gut mains and poly crosses for several months now. I think a natural gut main with a poly cross might give me that bit of extra pace and spin that I can't quite generate from a multi-filament string. If I were to go with a poly hybrid set up with poly in the mains or a full poly string job, I'd recommend keeping tension on the lower end (under 50 lbs for sure, probably start at 45 lbs and see how that worked).
For reference, my current frame is ProKennex Ki 5 (320), strung with natural gut mains at 58 lbs, ALU power soft poly crosses at 54 lbs. My racquet strung with overgrip and dampener comes in around 349 grams, so I was surprised the few extra grams on the 330 frame was enough to push me outside my comfort / ability to swing. Previously, I used the Babolat Pure Strike Project One racquet, but I gave it up when it started aggravating my elbow last year. I play at a 4.5 NTRP level, baseline player with top spin (counter puncher type style), strong semi-western forehand grip, one handed backhand.
I hope my review helps. I wanted to post my thoughts, as I know I appreciate all the other posters who take time to share their thoughts!