Sensor

Logitech uses their HERO sensor in most of their new mice, which is a fantastic tracking unit. It's very raw and responsive, extremely accurate, and doesn't seem to have any issues whatsoever. It doesn't feature any smoothing, filtering, or any kind of performance reduction. It's only fair to a legend's comeback to use an absolutely high-end sensor, and the HERO sure is one.

Now for some specifications: You can set the resolution from 100 to 16,000 CPI in steps of 50 CPI. The nominal maximum tracking speed and acceleration values are over 400 IPS and 40 G, which is insanely high; there is no way of hitting these values during regular use. The polling rate can be set to 125, 250, 500, and 1000 Hz, the latter being the default. As for the lift-off distance, the HERO sensor calibrates itself to the surface it's being used on automatically. In my opinion, some more customizability would be better here, but it did a good job on my configuration, so I don't mind this feature.

Paint Test

There is no jitter on the reasonable CPI steps, and I couldn't detect any unwanted angle snapping or sensor rattle either.

CPI Divergence

Thankfully, CPI divergence on this mouse is low compared to most newer gaming mice, and it also goes into the negative instead of being positive. Please note that this measurement is not 100% accurate as there is some human error involved, but the values resemble reality well.

Perfect Control Speed

Perfect control speed (or PCS for short) is extremely high on this sensor as 400 IPS is over 10 m/s. There is absolutely no way of hitting it while using the mouse regularly—I could barely hit 5 m/s on a 50 cm wide mouse pad.

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.

Polling Rate

The polling rate is nice and stable, without any suspicious periodic drops or outliers.

Input Lag & Smoothing

There is no smoothing, or anything funky going on with the sensor in terms of response time. I couldn't measure any input lag, which is as expected from the HERO sensor.

Click Latency

Click latency is roughly +4.2 ms compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. The data comes from this thread and my own testings (this review's chart only shows ergonomic right-handed mice). Testing was done with a Logitech G102 and the FPS Pro, using qsxcv's program.