Castor has the potential to be an excellent mouse. The hardware is all there, so let's see if the performance is on par.
The PMW 3310 sensor is excellent by default. It's outclassed only by PMW3366, which is currently found exclusively on Logitech's G502 Proteus Core. Mionix uses a bit of firmware wizardry, because by default the sensor should deliver an effective resolution of 5K DPI. Meanwhile, Castor boasts with its 10.000DPI, which is an impressive figure for sure - outclassed by the aforementioned PMW3366.
Of course, as CPI / DPI count looks impressive on paper - it's worth remembering it represents how many pixels the sensor registers in one inch. If you don't use multiple 4K monitor set-ups to justify the high count number, it should always be left to the side, and in its place other aspects be taken into account.
Aspects like hardware acceleration, tracking speed, or lift-off speed. I checked some of these with a few testing software packages avaible, but I should mention these usually pick up what the system receives, and not necessarily how the mouse behaves - meaning the hardware side, my hands are not going to be 100% accurate.
Still, with Enotus I got a max speed of 5.34m/s (close to the advertised - 5.45m/s - or 215 IPS), as well as excellent results in the other brackets. However, I should issue the warning, even if the results are Excellent / Positive across the board - take them with a grain of salt, since human error must also be taken into account - after all, my hands and fingers are 100% accurate in their movements.
As for hardware acceleration - neither positive or negative was noticed during several lengthy play sessions with games that register raw-input (Counter Strike, Quake, Battlefield with the option ticked). If such problems exist they're unnoticeable, or consistent.
When bringing new ergonomic shapes to the table, you have two options. Be a jack of all trades, or a master of one. Mionix's Naos was the perfect example of the latter - a peripheral dedicated mostly to palm-grip users with larger hands. Castor takes the other route (despite not being ambidextrous). There are subtle curves and definitions to suggest it could be used by most people, no matter how they hold a mouse in hand. For the most part, it's comfortable in hand, far better than Steelseries Rival (a similar offering).
The shape is smaller than a full-sized palm grip model, also quite light in hand. The ergonomic are properly positioned for all five fingers to land on the surface of the mouse. Yes, I would've liked the rear to be slightly flatter and longer for my large-ish hands, but even without them, I still ended up getting used to it quite quickly, and finding it comfortable.
I'm going to keep this short. Castor's sensor is excellent for shooters, at low & high DPI, depending on your preferences - particularly titles that take into account raw input (actually only those).
The 7 included buttons might not be good enough for people who want micro-keyboards on the side of their rodents, so they could have a library of scripts to play with. However, the extensive software customization should counterbalance this incovenience at least a little.