I have the Logitech MX700 (same as Jensked). I've had it for a couple of years now and it's great. As with Jensked, this used to be the top of the range when I bought it. It wasn't cheap, but it was worth it. My Mum also has one after trying mine (about 18 months ago, though it hasn't had daily use like mine). Dunno if that helps...
It's wireless, but I have never had noticeable lag problems from the mouse in my games - not that I've noticed anyway. More from crappy internet connection, so I wouldn't notice any advantage of the 518 on that side.
Enough buttons, etc. And I find it comfortable. Whenever I have to use a wired mouse now, I find the wire a real inconvenience.
As for the MX-1000, one of my housemates has it, and so of course I had to try it. It's definately very nice, it's more comfortable to grip than mine and the buttons are better.
The most important thing with regards to mice (and in fact any input device) is to go to a store and try it out for a bit. At the right angle too - the angle your hand will be when you're sat at a computer. Can you reach all the buttons comfortably etc? (though with these Logitech mice, you should be fine on that count)
Personally, I'd go for the MX-1000, as I certainly would not notice it being much slower than the 518. I also don't need the feature of the 518 to increase sensitivity on the fly. But most importantly, I don't think I'd want the added wire on the 518 either!
Oh, and unlike my current mouse (2xrechargable AA), the MX-1000 uses a built in proprietry (sp?) battery - longer life, less weight.
HTH
[Edit]
bigfoot1942 said:
SkylineGTR34 said:
If you're into gaming, get the MX518. Better choice is Razer Diamondback. (Fastest mouse.)
why would the razorback be better then the mx518? the optical part is exactly the same, so its all about which mouse you prefer (considering ergonomics and color)
Actually, it seems the MX518 is not as accurate as it still uses standard optical technology whereas the MX1000 uses laser tech. Supposed to be more accurate. But the MX518 has a very high refresh rate - much higher than most optical mice... But the optical part is not the same on these two... [/Edit]