This is amazing. There's so many great qualities to this mouse, but it's only worth the price to someone who can appreciate all aspects of the mouse.
I use a fairly high DPI by default, my normal being 3400 @ 1kHz poll on a 1920x1080 screen. Concerning gaming, well, depends on the sensitivity of the in-game movement. For games like Rainbow Six: Siege, I knock it down to 2000 DPI. High sensitivity games, I set it to 1100-1600 DPI. The majority of games I don't need to change it, though. I've never had a single stutter in movement that was the fault of the mouse. I typically have my mouse wired, but when movement is crucial (most FPS games), I'll plug in the wireless receiver at the end of the cord. Only stutter is that of switching between wired and wireless. As soon as it reconnects, I notice no difference in performance.
I've never changed the side buttons, being a right-handed user, and I keep the right-side buttons off. I often use these buttons for my own personal auto-clickers, melee, and reloading, so they see quite a bit of action. I've notice no degradation to the buttons in feel or performance. I especially enjoy the pivot-system for the left and right mouse buttons! Besides being a clearly better design that will last longer, because there is no bending of components, it's a very prominent, good-feeling click. The wheel has a very soft feel when scrolling, which is quite nice to me, along with the extremely-useful hyperscroll. Scroll left/right feels like it clicks twice, so after the first not-click I'll let go and it doesn't actually work, but they're not of much use to me in general, so they're not often used. I keep the DPI up/down buttons to their original functions, and don't see much action.
I personally feel that lighting is superfluous and unnecessary, except for when switching DPI, so I always keep them off.
Quite a light weight, the design isn't quite perfect for me. The way I hold my mouse, my pinky finger rests in the crease between the right mouse button and frame, which leave a nice mark after a while. Besides that, I've never had any noticeable cramping, except when I'm over-compensating my grip.
This mouse is most definitely overkill for the amount of gaming I do, but for MLG or serious players, this is incredibly worth it. For reference, I've owned this for 11 months and there's no degradation in performance or feel at all.