A Fn key. This means you lose a important programmable modifier key at a important spot. Bad for programers.
Azio Levetron Mech4 ＆ Mech5 Gaming Keyboard
The best thing about this one is that it features mechanical key switch. It uses Cherry MX Black, which is linear but requires more force.
other notable features/differences include:
Detachable number keypad. It can be attached to the left side.
Rotary wheel knob for sound level control. Nice.
A sliding rail for adjustable position of 6 programmable keys. Useful? am not sure. It's nice to have 6 extra programmable keys, but then it blocks 4 function keys. But you can take it off to be standalone.
Giant Enter ↵ key, but tiny ⌫ Backspace key, and \ is moved to top row, pressed by pinky. So, this keyboard won't be good for programers.
No dedicated multimedia keys or app launch key. This means, you'll have to “waste” on those programmable keys.
So, overall, this keyboard might be nice if you use it exclusively for gaming. It won't be good if you also do programing, or writing.
About the Cherry MX Black mechanical switch, i've tried it in stores, but didn't like it at all. But am not a dedicated gamer. I much prefer Cherry MX Brown, or Red. Possibly Blue too, which i haven't tried.
〔☛ Guide to Computer Keyboard Key Switch Mechanisms〕
The Mech5 model fixed the small backspace key problem.