Mechanical keyboards boast quick actuation and response time, which is great for FPS games. Although the difference is relatively small from other keyboards, the lower latency, low-pressure actuation, and rapid button return make keystrokes quick. The 6 key rollover enables 6 simultaneous button actuations, regardless of combination, something many keyboards will not reliably duplicate. This enables rapid simultaneous actions, including more versatile "WASD" movement, which allows you to move diagonally. The key rollover on other keyboards may not reliably register certain button combinations, and normally have a very limited rollover limit. The key rollover seemed to provide a bit of an advantage over our previous soft-dome actuated keyboards more so than the response time which is hard to notice from a normal-usage standpoint.
We tested the key rollover with a multitude of keyboard testing programs. These programs display a virtual keyboard which shows the registered keystrokes, and in USB mode the 6-key rollover worked without a flaw, and we weren't able to "trick" it with any particular key combinations. We also wanted to verify the N-key rollover (NKRO) in PS/2 mode, and, once again, the Quick Fire Rapid passed with flying colors, as it would register as many keys as we could press with our hands, elbows, and/or our face.
They keypress on the Quick Fire Rapid are soft where quick keypresses are easy, but the combination of the tactile "bump" feedback of actuation and the audible "click" feedback still enables a good feel of the keys themselves. One problem I've had in the past with very soft keys is that I felt relatively disconnected from the keys, but the Cherry MX Blue switches avoid these issues.