You've got two cams here:
the electraeon throttle cam mounts down by the injectors on the intake side of the motor. Think of it like the "slave cylinder" (if you make analogy to clutch hydraulics) in the relationship. You twist the the throttle grip, pulling the cable, which pulls the cam on the throttle body. The electraeon throttle cam shortens the distance from 0-100% in relation to the twist of your wrist when compared to the stock one (think of it as how many degrees the grip must be rotated to go from no throttle to wide-open). Also, its not plastic, its good looking billet and is somewhat visible through the frame on the side of the bike, just like the stock one.
the G2 Ergonomics throttle tamer, like any throttle tube, is the "master cylinder" and also has a cam. When you rotate the grip, you are directly rotating that cam, which pulls the cable - the amount the cable is actually pulled depends on both how far you rotate your grip, and the profile of the throttle tube's cam. The smaller the diameter of the cam, the less happens as you rotate the throttle grip. A fast throttle has a larger 'diameter' profile - meaning that it will pull more cable for the same amount of rotation. The G2 Ergo throttle tamer has a throttle tube cam profile that increases in radius as it goes, making it slower at the beginning of rotation (less cable pull per degree of rotation), but increasing the further you go (as you rotate further, the increase per degree in amount of cable pulled increases - think of derivatives and calculus and such).
Alternatively, you could think of a throttle cam with changing radius to the cam profile to work similar to progressive springs:
http://www.progressivesuspension.com/tech/springs.html (perhaps think of the progressive spring description as applied to throttle cam: as you twist further, the amount it pulls doesn't increase linearly).
Neither product is all that expensive. I might suggest acquiring both, installing only one and riding around awhile to see how it affects the bike. Removing it and ride without for a bit. (go back to baseline). Install the other alone, ride around a bit to see the change. Then installing the other with it so you can try the bike with both. Only way to get a full picture and see if you like the changes in characteristics with regards to your riding style / preferences.
