When I first got the M3 4K, I was quite underwhelmed by the performance. Between severe polling instability and randomly increasing motion delay, one issue in particular stood out: At polling rates of 1000 Hz and under, input loss happened relatively frequently. Essentially, polls were delayed to where an input effectively was ignored, resulting in the cursor not moving and guns not shooting in-game. With such a grave issue, I was ready to give the M3 4K a bad review, but thankfully, combing the internet I've stumbled upon a new firmware. While not available through Darmoshark's own site, this firmware not only fixed all but one of the aforementioned issues, it even improved click latency to a non-negligible degree.

With said firmware, the M3 4K is finally able to shine. CPI deviation is appreciably low, general tracking fine, and motion delay excellent across the board, with 2000 and 4000 Hz expectedly improving things even further. In wireless (2.4 GHz) operation at 1000 Hz and without MotionSync, the M3 4K is typically 0.5 ms behind the Logitech G403 (control subject), and at 2000 and 4000 Hz, slightly ahead of it. Upon enabling MotionSync, which synchronizes SPI reads with USB polling events, motion delay is increased, as a motion delay penalty roughly equal to half of the set polling interval is added. The excellence in terms of motion delay is matched by the click latency. At 1000 Hz in wireless operation and using the lowest debounce time setting, click latency is just 0.7 ms, and if set to 2000 or 4000 Hz, gets even lower at 0.6 and 0.5 ms, respectively. Among 4000 Hz wireless mice, this level has before only been achieved by Razer. In addition, much like Razer or Logitech mice, the M3 4K has rudimentary lift-off detection implemented, which sets 8 ms of defer-type debouncing upon lift-off state regardless of the set time for the non-lifted state, ensuring no slam-clicking even at the lowest debounce time value. Compared to competitors such as the LAMZU Atlantis 4K or VGN Dragonfly F1 Pro Max, where the lowest possible click latency inevitably brings slam-clicking with it, this is a clear advantage for the M3 4K. While the firmware fixes much, one issue remains, which is polling stability. Across all polling rates, the M3 4K suffers from off-period polls occurring at a fixed interval of 1 ms, along with bursts of generally increased noise. Thankfully, this merely affects motion but not click events, therefore only worsening perceived smoothness to a minor degree.

The wireless experience on the M3 4K is quite pleasing. Charging is fairly speedy, and the charging cable flexible to where playing while charging is possible without feeling overly restricted. Unfortunately, battery life on the M3 4K is a bit of a mystery. Darmoshark provides no numbers whatsoever, and the battery charge indicator within the software is either not functional or lacking in precision to where it becomes all but useless, as even after extended usage at 4000 Hz, it still showed 100% for me. The wireless dongle also serves as a basic battery charge indicator in that an LED lights up in three colors corresponding to three rough charge states, though this too only showed "green" (the first stage) in my testing. That said, the M3 4K does feature an 800 mAh battery, which should result in non-terrible battery life at least.

As a result of the larger battery, at 66 g, the M3 4K weighs a decent bit more than the regular M3. In terms of shell design, the M3 4K leaves room for optimization. Since Darmoshark has opted to re-use the same shell previously used for the M3, the M3 4K even features the same dongle storage compartment, even though no such dongle that would fit in there is included on the M3 4K. Moreover, there is some minor rattle when shaking the mouse on my sample, along with creaking of the shell when applying lateral pressure. More importantly, the sides have a decent amount of flex, and actuating the side buttons by pressing below them doesn't require all that much force, albeit enough that I didn't encounter issues during regular use. The feet likewise are unchanged compared to the M3 and continue to glide well, and much like before, a set of replacement feet is included with the mouse, in addition to a set of grip tape.

The M3 4K comes with TTC Gold switches for the main buttons, which aren't as tactile as Kailh GM 8.0, but typically less prone to developing double-clicking over time, and some pre-travel aside, button response is firm and snappy. The button design itself is also competent, as the buttons don't have much lateral play, even when forcing it manually. For the side buttons, Darmoshark has opted for switches from TTC as well, which score with low pre and moderate post-travel, along with even actuation. The scroll wheel encoder also comes from TTC (yellow or "Gold"), though compared to previous mice using this encoder, it behaves somewhat uncharacteristically in the M3 4K. Noise levels are relatively low, but tactility is somewhat lacking and closer to what a TTC Silver feels like. Whether this is by design or just an instance of unit-to-unit variation, I don't know. In any case, the switch choice on the M3 4K wouldn't look out of place on a $100 mouse, as even the scroll wheel switch is a full-sized mechanical rather than a tactile switch.

The software of the M3 4K is among the very few not requiring installation. While it looks quite rough, with spelling errors everywhere and a Glorious Core knock-off UI, I have little to complain about in regard to functionality. Occasionally, it appears that settings aren't applied correctly, but other than that, everything important is present and works, and resource usage is pleasantly low throughout.

Overall, the M3 4K serves as a great example how much the firmware can make or break a mouse. On the launch firmware, the M3 4K essentially is broken, yet the right firmware transforms it into a contender for Razer's $150 offerings in terms of performance. Priced at $69.99 on Mechkeys.com, the M3 4K only enjoys competition from the VGN Dragonfly F1 Pro Max within the 4000 Hz wireless mice space in terms of value, which delivers comparably excellent performance at the same price point when including the 4K dongle, but fares a bit better in terms of build quality. Of course, much like with VGN, one has to lower one's sights when it comes to warranty or customer service on the M3 4K, but at this price point, I'd argue that this can be forgiven. As such, the M3 4K earns our Recommended and Budget awards.