It's a good skill to have. I think sysadmins kind of acquire it naturally, with much work being done in the terminal. I'm fairly proficient on my own computer with my own hotkeys, though I'm sure I could take it further with some effort. I still use a mouse frequently in the browser, but for the bulk of my work my hands don't leave the keyboard.

I'm not sure whether it's significantly faster than an "expert mouse user" but I also don't think it's slower. I haughtily think that my killing and yanking is more precise than it would be clicking, but who knows?

I think it's kind of a parlor trick really, but it does impress the younger and less experienced team members to some degree.