I am that weird guy that has eschewed using a mouse in favour of a
trackball, which has been the case for well over 10 years now. Yes, even for FPS. It probably affects my gameplay, but I'm not trying to break into e-sports or any of that nonsense so I haven't really ever felt like it's been too much of a hindrance.
I switched to a
mechanical keyboard for the first time less than a year ago, and I love everything about it. It feels so much easier and more fluid to type with to the point where I notice how much worse my old keyboard is by comparison whenever I have to use it, as it's hooked up to an old computer in the basement.
The most specialized input device I have is an
arcade stick which gets a lot of use for Street Fighter. I eventually reached a point where I felt my performance was being negatively impacted by using the awful 360 pad and couldn't take it anymore. In retrospect, it was well worth the investment.
Jam it back in, in the dark.