I would compile it like this:
- Macro keys = not gaming. I use my G19 macros for work
- Backlight = not gaming. This is an allround feature.
- Mech keys = not gaming.
- headphones plugs = not gaming
- USB ports = not gaming
- LCD display (G15/G19, etc) = allround feature (I at least never use it for games, but for monitoring, pictures and news wire...
- Keys' aspect changes to suit specific games, removing letters, adding icons... = gaming
- More or less revolutionary Layout changes to make WASD'ing easier (like Fang) = gaming
- Spaceship, mechwarrior or submachinegun looks etc = gaming
If I was a gamer only, and not an allround computer user, I would get something like a Fang+mouse+SMALLEST POSSIBLE KEYBOARD (only for login and mail purposes).
Of course it totally depends of WHAT kind of games, Formula 1, flight sim, BF3 and role playing have totally different needs. So we return to the beginning: Can we call a keyboard a "gaming" one?