It is quite obvious that this mouse is for RPG games since its button placement gets in the way of efficiently lifting the mouse up. Leetgion is totally upfront about its target audience with this mouse: it is for Diablo III and similar MMORPGs. This design is definitely not for everyone and makes the mouse perform poorly with all FPS titles. That being said, you can still play FPS games with the El'Druin, but it will require you to change your play style of playing and grip, which would be too much of a hassle for most FPS gamers.
The mouse uses the Avago ADNS-9500 sensor: one of the best-performing sensors on the market, and the implementation is well executed. All of its main characteristics, like low lift-off distance (LOD), very high failure speeds, and the positive acceleration issue, are still present.
Gaming
In-game tests with this mouse were limited to CS:GO and Diablo III. It makes sense to test the mouse with Diablo III because the mouse is built for such games. The CS:GO test was solely conducted to gauge the core performance of the mouse in regards to tracking.
First up was a lengthy session in Diablo III. The mouse proved to be interesting, since you can map a lot of neat stuff to the four-way button. It lets you swap spells out easily and gives you faster access to some of the more menu-buried functions in Diablo III. The macro system works alright if you are into that sort of thing. Personally, I am not for spending a lot of time setting it up, but it might be worth the trouble if you play RPGs competitively. The S-Pad, once properly set up with appropriate button assignments and a little in-game testing, made for quite a good mouse to play with, although the shape and its functions take a lot of time to get used to. Most of the annoyances were gone after a week of testing, but the S-Pad still felt a bit awkward. Its placement compromises both grip and in-game ergonomics somewhat, making it hard for people with larger than average hands to get the most out of the mouse because it is placed too far towards the back of the mouse.
The primary buttons are great. Their lower-than-average actuation force and slightly longer travel time works well in RPG games with a lot of key strokes, like Diablo III. That together with the S-Pad makes this mouse a serious kit for Diablo III but a horrible mouse for FPS games and ordinary desktop use.
The right side's secondary scroll wheel is almost impossible to use properly, since you have to use it with your ring finger or pinky. Placing it a little further forward would make it so much more efficient. It leaves a lot to be desired in its current implementation.
Desktop Work
We would have loved to see a way to integrate left/right and up/down sensor movement into macros, since that would allow you to create a very neat CAD work profile for SolidWorks, Pro Engineer, or any other CAD software. It would be ideal if you could get the S-Pad to mimic a 3Dconnexion desktop controller; however, that is not possible with this driver suite, but may be an excellent idea worth looking into. You can, however, get past this issue in SolidWorks by assigning ALT + Arrow keys to get component reorientation to work.