I have a MX500....it is way better than the MX710. I don't know about the MX1000 though. I don't really think that it can be all that much better though.
The MX1000 is superior in terms of the sensitivity! It does not use the classical optical technology but rather a class 1 laser device. That means it samples things at a microscopic level and does an overall better job. However, the mouse is not the best of gaming due to its weight and a slight delay when the mouse is lifted.
Man, what's it matter? I have a MS Optical Mouse 2.0 and I've been happy with it for both gamming and desktop useage. I don't see why people need something more much sensitive than say this mouse... I don't know how heavy those Logitec mice are, but this one uses AA batteries and isn't too bad. It is a bit more heavy than my cheap Memorex, but it lasts about 20x as long!
The nicest thing that I know of that the MX1000 gives you over the MX500 is the precise tracking of the movement of the mouse, and the onboard battery meter so you can see how much battery life is left, as well as the recharger station. Overall, that mouse is definitely worth the about $80 that it'll cost...
i have the MX510, and i love it, it doesnt have adjustable sensitivity, but i wouldnt want it since i very rarely adjust the sensitivity, anyways, it is great for gaming, i love all the buttons and it looks awsome!
man ive got the mx1000 and trust me i am very happy man i reccomend it , trhe price is a little high for mouse but if ya got the money i reckon go for it