Setup, Design & Observations
Ventus R
The first thing people will notice with the Ventus R is how light and small it is. While it isn't a tiny mouse, it is certainly smaller than what many may be used to and so may deter people that prefer larger, heavier, palm grip orientated mice. Though fans of high speed, claw or finger tip grip mice will love the feel of the surface, and the rubber side grips Tt eSPORTS have chosen to use. This mouse is ambidextrous, however left-handers will have to forego the use of the convenient side buttons.
The mouse clicks are fast and feel satisfying to press, something that extends to the side buttons also (despite creating a loud hollow clicking sound). The mouse wheel scrolls fantastically but feels a little strange when pressed, having a very short and stiff actuation. I couldn't find a way to adjust the DPI on-the-fly which was a minor inconvenience, there was no way mentioned in the guide, nor combination of buttons (like hold mouse wheel + right click) that seemed to work.
The only thing we noticed that could be annoying was that the front of the base narrows a lot compared to the top of the mouse, combined with the narrower still slip pad that is raised a fair bit off of the base (maybe 1mm), in use we observed that without a secure grip, it was easy to rock and tilt the mouse off its based, so a poorly placed click could have detrimental effects on tracking in game. It isn't something we had a problem with in practice, but it was certainly noticeable and I found myself rocking the mouse side to side on purpose just because it was easy to do.
Ventus Z
In contrast to the Ventus R, the Ventus Z is a palm grip mouse that is is shaped for comfort, and is significantly heavier. This will cater for those that prefer palm grip mice. If you prefer it to be slightly lighter than the 130g, you can remove the 3x 4.5g weights. We preferred the mouse without the weights because we found that it was a little rear heavy which could cause a slight problem with torsional motion (the front end is easier to move than the rear, causing a twist in motion causing tracking issues). This isn't something many people will notice or have a problem with, but we preferred the balance without the weights.
The Ventus Z features five additional programmable buttons including a sniper button, copy/paste button, and profile up/down button. the copy/paste buttons are placed convenient for your index finger to press, and as with the Ventus R, each button feels great and satisfying. Though the mouse wheel again, feels fantastic to scroll, but is a little stiff in its actuation.
Another recurring feature is that the Ventus Z is a little easy to roll specifically when using the top side copy/paste buttons. Generally having a very stable base that will allow any required down force upon the mouse without the mouse flipping, tilting or rolling is good design practice. Comparatively, the Ventus Z isn't as unstable as the Ventus R, likely due to its size and weight.

Performance
Ventus R
The tracking performance of the PWM 3310 sensor is fantastic, and in reasonable DPI ranges up to 3200, it is entirely smooth and jitter free, while at the maximum of 5000DPI, a small amount of jitter is introduced, but the MCU keeps it under control and is perfectly usable. The 3310 sensor tracks perfectly well on most surfaces, we tested it on a standard black fabric mouse matt, white paper, glossy wood veneer desk, and coloured paper and it handed that all perfectly.
In game the mouse was a joy to use, responsive, accurate, comfortable and reliable. The unstable base didn't really make any noticeable impact in game on DOTA2 or CS:GO, and I realised that this mouse has a very low lift off distance, which helps to negate any lift-off travel that may be caused.
Ventus Z
The Ventus Z features the AVAGO 9500 laser sensor, and like its big brother, the 9800, we found that it tracks perfectly across most surfaces. Though we did find that it was slightly more jittery on the glossy wood veneer (bare desktop). The DPI rating is a little ambitious, considering the amount of jitter it has. We see a small amount of jitter enter around 2000 DPI and gradually becomes stronger as the DPI increases. 3200DPI is certainly usable, though I would recommend against using this mouse at a high resolution.
Starting some matches in DOTA2 the mouse remained comfortable and easy to use, however, in CS:GO, I started noticing a strange acceleration property where, if you accelerate too quickly the mouse kinda slows itself down, like it is using some kind of anti-acceleration setting enabled to compensate for any hardware acceleration of the laser sensor.