I got to play with the HD, Blade, and GravityPro (GP) last night. Too bad they're all strung with different strings -- syn gut on the HD, RPM Blast on the Blade, and some poly/multi hybrid on GP.
For background: I play with Angell K7 Lime slightly modified to approx. 343g, 325 sw. I played with all 3 frames last night during my USTA 8.5 combo team practice so I played against a 4.5/4.0 player. In stock form, I just don't gel with the GP. That's the easiest one to rule out. It just feels sluggish. As for the HD, as many people have said already, it's a soft, low-powered frame. It means that this frame needs a proper technique and a full swing..... on every shot. 20mm beam gives a lot of feel but also very little power. Imho, even though anyone can play with this frame, not everyone will be able to get the most out of it. It's a great doubles stick though; just amazing at the net and maneuverable. I'm adding some tape tonight (at 12) to beef up the SW and see how it plays, particularly on serve. But I've pretty much decided I'm not switching to it.
Agree with
@Power Player , the Blade is the better frame off the shelf. It's a bit more "practical" frame so to speak, it's very usable for recreational players. Good power, easy to swing, great feel, good sweet spot, hits a heavier ball, etc. I'm going to add some weight at the handle since I'm used to 7-8 pts HL.
The HD reminds me of why I sold my RF97. The RF was an awesome stick...... at least in the 1st set. But the sweet spot felt like getting smaller and smaller as the match went on. Playing a long, deuce game in the 3rd set? I felt every ounce of the weight. It was obviously user error, I didn't move my feet as the match went on. Lesson learned -- I've taken a realistic approach in evaluating a new racquet and accept the fact that I'm not good enough to wield some racquets. Oh well.