So, you've bought a gaming mouse, so isn't the big test how it performs in games, unless you bought it for huge multi-monitor setups to utilize the freakishly high DPI potential? If I sound like I'm gushing a bit, forgive me, but this is where the Sensei shines... brightly. The onboard ARM processor and the accompanying SteelSeries Engine software are what sets the Sensei apart. The Exact Lift, ExactAccell, and the ExactAim features are incredible, and force the words "competitive advantage" into my mind.
Where it gets amazing is that DPI-selection was originally incorporated into mice to provide different sensitivities for dynamic game situations, such as fast for the run-n-gun player, and the next life a low sensitivity for the dialed-in sniper. Where SteelSeries has changed the game is that you can do both with one setting on one profile. I have the ExactAim dialed all the way up, what this does for me is that when I move the mouse slowly, my DPI setting is kinda-sorta negatively accelerated to have a lower DPI, but using ExactAccell and my desired DPI setting, I can fine-tune how rapidly my cursor speeds up with more rapid movements. This means, depending on how I move my mouse, I've got the stable hand of a sniper to the fastest twitch needed to defensively turn 360 degrees to engage a flanking enemy.
Then, there's the use of Macros. Macros tend not to be as useful in FPS games, but the potential for what I'll refer to as "burst click" adds another advantage. You could macro the left mouse button to be a double or triple left-click for burst fire with a single click. The potential for customization is essentially unlimited, and could be used in any number of creative ways.
We have limited usage in RPG games, but the high polling rates and precise, accurate tracking from the Sensei's dual sensors makes it a great match for many RPGs and the macro-potential using the software makes it a great choice in RPG games as well.
The high polling rate creates a smooth and quick response which I quickly noticed, even if it was a subtle difference from what I've previously used.
The Sensei brings less advantage in normal usage, unless you're using a high resolution multi-monitor setup which takes advantage of the high DPI sensitivities which are possible with the Sensei. The sensors track very accurately and precisely on all of the surfaces we tried it on, which ranged from glass and wood and even to a wicker end table. The high polling rate produces a "buttery" response which is very smooth.