In most MMOs and FPSs your left hand is on the WASD keys and your right hand is on the mouse. (Reverse of course for left-handed people.)
This means that it is very important for as many keys as possible to be reachable from the left hand as effortlessly as possible.
The 82-key keyboard is superior for WASD-centric gaming because the function keys are all a lot closer to WASD (i.e., there is no gap between the number key row and the function key row, there is no gap between ESC and F1 or F4 and F5, etc.). So I got one of these.
However, the 82-key keyboard could be significantly improved with a few changes:
The movement of the `/~ key down below is not a good one. That key is very easily hit from the WASD configuration and should be returned.
SUGGESTION: Move `/~ back to its normal place on the 82-key keyboard, make the TAB key and other left keys wider like on the 104-key to make room.
I make heavy use of key combinations with the ALT key. However, the ALT key on the 82-key is too far to the left and it is too small.
SUGGESTION: Make the spacebar smaller, make the left ALT key bigger, and move it to the right. The thumb should be able to easily depress the ALT key while the fingers are centered on WASD at the same time. You should not need to roll your thumb under your palm excessively while doing this as this is uncomfortable and detracts from gaming. (Note, I currently use key-rebinding software to rebind the `/~ key to ALT, and even that is far too much to the left.)
Other nice to haves, not not required, would be this same layout in a tenkeyless version. When using two-hands on the keyboard for regular typing, a tenkeyless version is a lot more natural to use for me than the ultra-compact 82-key version. (The 104-key is too large though.)
In general, when designing your keyboards please design them around the notion that only one hand is on the keyboard while gaming. The left-hand position is very important.