Sensor

Since the other specifications are so well thought out, and the whole mouse features some rather unique and innovative solutions, it would be a letdown to use a mediocre sensor for the tracking. Needless to say, this is not the case as the Model O features a PixArt PMW3360 optical sensor, which is still among the best sensors available today. It's raw, responsive, and doesn't have any added acceleration, filtering, or other performance-reducing gimmicks. There's some smoothing on and above 2100 CPI, which is usually the case with most newer PixArt sensors, and it's there to reduce jittering on higher resolutions.

Now for some specifications: the nominal maximum tracking speed and acceleration values are 250 IPS and 50 G, which are ridiculously high; there is no way of hitting these values during regular use. Resolution can be set from 100–12,000 CPI in steps of 100 CPI. The available polling rates are 1000, 500, 250, and 125 Hz, which translate to 1, 2, 4, or 8 ms of nominal response time respectively. Lift-off distance can be set to 2 and 3 mm in the software—the former doesn't track from 1 DVD in height, and the latter doesn't track from a stack of 2 DVDs.

Paint Test

There is no jitter on the reasonable CPI steps, and I couldn't detect any unwanted angle snapping, either. I did measure a minuscule amount of sensor lens rattle, which resulted in a pixel of horizontal movement on 12,000 CPI, while the mouse was being shaken with great force. This shouldn't cause any problems during regular use and isn't audible either.

CPI Divergence

CPI divergence is not too high on this model and even goes into the negative region. While most mice tend to have slightly higher actual CPI than the CPI they are set to, the exact opposite is the case on the Model O.

Perfect Control Speed

Perfect control speed (or PCS for short) is extremely high on this sensor as 250 IPS is over 6.35 m/s. There is absolutely no way of hitting such a high value during regular use, so this sensor won't spin out if you land a huge swipe.

Speed Related Accuracy Variance

This test shows the sensor's accuracy at different speeds. You can see me doing a fast swipe to the right before I slowly slide the mouse back to its original position. There is pretty much no acceleration or deceleration here, or if there is any, it's due to human error.

Polling Rate & Stability

All polling rate values are nice and stable, without any suspicious outliers or periodic drops.

Input Lag & Smoothing

There is no measurable smoothing or any other delay below 2,100 CPI. At 2100 CPI, some smoothing kicks in, resulting in about +1–2 ms of input lag, which doesn't correlate with increasing the resolution. Albeit a negligible amount of smoothing most users won't notice, I would highly advise staying on a CPI step without smoothing for competitive gaming. For anything else, feel free to use whatever you like, within reasonable bounds.

Click Latency

Click latency is roughly 4.1 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. The data comes from this thread and my own testings. Testing was done with a Logitech G100s and the Model O, using qsxcv's program. This value is achieved by setting the debounce time to 4 ms in the software; by default, it's about +11.8 ms.