The Endgame Gear XM1 RGB is the third iteration of the XM1. For the XM1, Endgame Gear opted for a minimalist approach: no RGB lighting, on-device adjustability, and barebones software customization. The XM1 RGB, on the other hand, aims to appeal to those fond of having some RGB lights on their rodent of choice. As far as the basics go, the XM1 RGB is no different from the regular XM1. Same shell and shape, same coating, same top-tier sensor, same scroll wheel, same side buttons, same highly flexible cable, same quality mouse feet, and the same analog click technology that ensures very low latency while eliminating any risks of double-clicking.

The differences lie in the lighting and switch department. While the main buttons on the XM1 were very good, they had a certain hollowness to them, which isn't everyone's cup of tea. The XM1 RGB presents itself much improved in this regard, no doubt thanks to the new Kailh GM 4.0 switches which have been pre-selected for lower operating force. Additionally, a new switch is used for the middle mouse button (scroll wheel click). It is easier to actuate as well, though I found it rather odd in terms of feel. The biggest addition, of course, is the RGB lighting. There's a decent range of nicely varied lighting effects to choose from, along with a fair number of customization options within the software. I have to admit I'm a bit disappointed by the implementation, however. The default "Color Flow" lighting effect in particular negatively affects both polling rate stability and tracking quality, and although the impact on performance is minimal, I had still hoped for a flawless implementation of the RGB lighting on the XM1 RGB, much like in every other area. The necessity to disable RGB lighting in order to get polling stability that matches the regular XM1 kind of defeats the purpose of having RGB lighting in the first place. The weight added by the addition of RGB is rather substantial, too—82 g isn't heavy, but it's no doubt a far cry from the 70 g of the regular XM1.

In summary, the XM1 RGB is a bit of a mixed bag. It's an excellent mouse still, but seeing it struggle in the RGB lighting domain, the very domain that sets it apart from the regular XM1, is disappointing. Just to be clear, performance is barely affected, but for an enthusiast mouse, I expect performance to stay the same no matter if RGB is enabled or not. On the other hand, the new main button switches no doubt are a profound improvement, and for now at least these are exclusive to the XM1 RGB. For what it's worth, Endgame Gear plans to thoroughly revise the firmware and software for their entire XM1 line, which will address the polling rate woes on the XM1 RGB. As of now, despite the improved main buttons, I'd still opt for the regular XM1 over the XM1 RGB, if only for the lower weight and peace of mind brought on by the flawless sensor performance, as well as the lower price.