Best Mouse Evah!
I got a drawer full of the things. Commodities if you ask me.
It's not something I say lightly having tried too damned many mice and always finding an issue with them. If there's an issue with this mouse - I can't find it.
Other than not gripping it tight enough when I reposition it(which I've fixed, got accustomed to it being more narrow at the top and gripping tighter because of how smooth the rubber is) the only other thing is the buttons are seriously sensitive. I got used to the Xai requiring a lot of force to click, just moving the mouse I accidentally set off the right mouse button occasionally. I'm not used to a mouse requiring such light pressure to click, can't think of one really that's close in that regard. I can spam clicks roughly 3-4 times faster than the Xai because of it. Joy!
The left/right clicks are on a hair trigger. The mouse wheel(<3 defined steps when scrolling up and down) and back/forward buttons are exactly the same force required as the Xai, not too much and not too light - just right.
Stuff about mx518 durability.
The original DeathAdder, G5 and G9 I own have outlived every other mouse I've had, though obviously they haven't received much usage lately since I got my Xai months ago. I'm generally pretty good with keeping peripherals in good condition though.
I'd say any of Logitechs, gaming mice at least, would be durable. Generally pretty good customer service too. Bang for the buck the MX 518 is one of the better deals currently easily.