Sensor

Both the Flick 2 and Clutch 2 use the PixArt PMW3360, which is an absolutely top-of-the-line optical sensor. It provides raw, responsive, and perfect tracking with an insanely high perfect control speed. The firmware is also very well written for the Clutch 2, and just like with the Flick 2, there is only the small issue with the polling rate, which you can read about in its own section.

The maximum nominal tracking speed and acceleration values are 250 IPS and 50 G. You can set the resolution from 100 to 12,000 CPI in increments of 100 CPI. The available polling rates are 125, 250, 500, and 1000, which translates to respective nominal response times of 8 ms, 4 ms, 2 ms, and 1 ms. There are two lift-off distance settings, 2 mm and 3 mm. You should stick with the 2 mm setting unless you experience tracking anomalies, which shouldn't happen on a proper mouse pad.

Paint Test

I didn't experience any jitter on the reasonable CPI steps, and there is no unwanted angle snapping either; there is an option for the latter, but for gaming, I highly suggest turning it off. There isn't any sensor lens rattle either.

CPI Divergence

CPI divergence on the Clutch 2 is a tad better than the average; the measured values are quite accurate, only a bit higher than the nominal ones. Please note that this test is not 100% accurate, but resembles reality well.

Perfect Control Speed

With around 6.5 m/s, perfect control speed (or PCS for short) is very high on the PMW3360—there is just no way of hitting this value while gaming at even the lowest in-game sensitivity setting. The PCS values don't correlate with the set resolution, which means 400 and 12,000 CPI both hit their limits at about the same value.

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 no acceleration or deceleration as any displacement is almost entirely caused by human error in this test.

Polling Rate

From 125 to 500 Hz, the polling rate values seem to be nice and stable; there are no suspicious outliers or periodic drops. At 1000 Hz, there are some spikes I don't really understand, but I think it might be a firmware-related issue. It didn't cause me any problems while gaming (I tested the mouse mostly with Quake Live and CS:GO).

Input Lag

There is no smoothing or input lag on or below the 2000 CPI step. Right above that value, the PMW3360's smoothing kicks in, which adds about 2 ms of input lag. While negligible, I would highly suggest staying on or below 2000 CPI for competitive online gaming.

Click Latency

The click latency is roughly +4.5 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 test was done with covered lenses on the newest (1.1.118) firmware, in comparison to the Logitech G102. +4.5 ms can be considered quite low compared to the competition.