Just finished playing a few sets of dubs and 2 sets of singles with the VC100.21+.
Yonex Precision Scan specs:
Unstrung/Strung Swing Weight: 306/338 kg/cm2
Effective Unstrung/Strung Swing Weight: 323.5/352.7 kg/cm2
Weight Unstrung/Strung as played: 300.5/321.7 gm
Unstrung/Strung Balance: 333/340 mm
L/R weight: 72.5/72.8
String: Volkl V-Torque Tour 1.10mm mains 53lbs, Tecnifibre Pro Red Code Wax 1.20mm crosses 50lbs
From what I remember of the SV100+, and the VC100.18+, the .21 version plays more similarly to the .18 than the SV. The VC100.21+ is just under 3 pts headlight, with a Wilson overgrip on it. That's the only mod I put on. Off the ground, it was quite whippy (my usual spec is 344+g) and the string pattern does have good grip. However it does leave the string bed in a hurry, like the previous version. That, combined with power, and the higher launch angle, players will have to be a tad more aggressive with the angle they contact the ball to keep the control of depth at full swings, which can affect consistency. The nice side effect of that is I never felt the need to swing out 100%, even on scrambling shots. Inside the court, the bite and power made it difficult for me to be ultra aggressive going for short angles with power, but still had good spin. Feel was muted, compared to the VC100.18+, but I could still feel a smidge of string movement.
At net, it is very lively and grippy, which I had to adjust for incoming heavy spin passing shots. The first few volleys I messed up in game play because the heavy spin caught the strings and affected my trajectory. Once I adjusted, it was a competent punch and drive volley stick, especially the overheads where I liked the snappiness of the frame and grip of the strings. The only time I felt the extra length/swing weight impeded the stroke was on the high backhand smash, where snapping the wrist was a little too sluggish with the added heft.
The serve is where I suspect most people will appreciate this racquet the most. It has great power and spin potential, and combined with decent mechanics, it can boost the serve. I especially liked the flatter wide ad court serve, because the added power meant I could hit the sideline 3-4 ft above the bottom line more often, something I struggle to do above 55% the time and definitely with less overall speed.
Overall, it's just too powerful for me to use right now, since I'd have to hit with extra aggressively closed racquet face to temper that added power, and the muted feel is just not helpful in grooving into the racquet quickly. The 16x19 pattern is nice and grippy, with a livably high launch angle (compared to my 16x20 SV98+), and the serving is awesome with this stick, so it would work well for those looking for a power stick.
I should add I have to restring it after the 4th set. The string pattern is open and has a high launch but not Babolat high.