I have to agree with RCoon. I use a membrane type keyboard from Microsoft which I bought more than 5 years ago because I loved the tactile feel of the keys. The only thing that really interests me in keyboards is whether I like the "feel" of the keys or not. The only other criteria that I could see myself looking for is rollover, because I think that certain games which require many simultaneous key presses could be handicapped by a cheap keyboard with a low rollover count. Anything else, like displays, excessive macro buttons or backlight are purely gimmicks for me and not worth the money.
Mechanical keyboards for me, personally, are a preference thing. I don't believe that you can game quantifiably better by using a mechanical keyboard. On the contrary, I believe that for gaming any key technology can do, but if you type a lot at a high speed then you will probably prefer the actuation of mechanical keys.
EDIT: Oh, and my girlfriend would probably kill me if I would buy a mechanical keyboard. She's noise sensitive
And to clarify: I do game, and not just a little.