The Ironclaw's PMW3391 sensor is presumably a variant of Pixart's PMW3360, and the Harpoon RGB Wireless seems to have a PMW3360 variant as well, but not the same one as the Ironclaw. The sensor in the Harpoon RGB Wireless is designated as the PMW3325 and has a max CPI of 10,000, as opposed to the PMW3391's 18,000 max CPI. However, unless you'd like to set your CPI higher than 10,000, the PMW3325 shouldn't let you down.
When using a wireless mouse, you have to consider the sensor in conjunction with the speed of the wireless connection, but the Harpoon RGB Wireless served me well in the twitchy, high-adrenaline FPS, Ironsight. I never noticed any kind of delay or connectivity issue at all. Both the sensor and the wireless connection seem to be reliable.
Unsurprisingly, I was unable to make the sensor lose tracking or spin out. The PMW3325 also showed itself to have zero innate mouse acceleration in my one-to-one tracking test. When moving back and forth between two books, the crosshair consistently targeted the same two bullet holes in the CS:GO training grounds. I use CS:GO for this test because you can enable raw input and disable mouse acceleration in the settings.
If there's anything strange going on with the data coming from a mouse, MouseTester is a handy way to sniff it out by mapping raw data onto comprehensible graphs. The data collection process involves speedily sweeping a mouse back and forth. Impressively, while connected wirelessly, the Harpoon RGB Wireless' PMW3325 produced smoother curves with fewer irregularities than the PMW3391 in the wired Ironclaw. Even on the millisecond scale, the mouse's wireless connection doesn't seem to hinder the sensor from shining.
The data we collected with MouseTester also shows that the sensor's max polling rate is 1000Hz, as advertised.
Quickly free-handing lines and curves in MS Paint can be used to test for angle snapping. Thanks to the prevalence of human error, suspiciously straight lines, as well as angular curves, are a giveaway that angle snapping is occuring. As you can clearly tell from the image above, no angle-snapping has messed with the curves or corrected my failed attempt to draw straight lines. The PMW3325's lack of innate angle snapping and mouse acceleration makes it an ideal sensor for building muscle memory.
The gist of my comments on iCUE in my Ironclaw review is that iCUE gets the job done, but it's somewhat clunky. It may take a bit of searching and a couple of extra steps to accomplish your goal.
The Harpoon RGB has been in Corsair's lineup for a while, but the addition of wireless connectivity makes it a compelling option in the portable mouse space thanks to its small size. The Bluetooth connectivity issue needs to be addressed, but the Harpoon RGB Wireless is otherwise pretty much perfect. I'm grasping at straws when I say the back side button could be moved down just a tad. Small mice can be cramped and awkward, but the Harpoon remained pleasant to use over extended periods of time. The sensor is top notch, and the wireless connection is lightning fast. The buttons are reassuringly clicky, and the USB receiver compartment on the bottom of the mouse is super handy. If you turn off the LEDs, you can bring the battery life all the way up to a solid sixty hours. You will have to deal with the kind of unwieldy software in order to turn the lights off, but you can set it and forget it.
The build quality, shape, sensor, and side buttons all set it apart from the great many chintzy portable mice out there. I think the Harpoon RGB Wireless is a fantastic option for people on the go who value a well-built, portable mouse that's comfortable. It's become my personal go-to portable mouse. You can pick it up for just $50, but if you're just a fan of small mice and don't care about the wireless functionality, you can snag the wired version for $30.