I have the original corded incarnation of this mouse. I bought it as a replacement to my MX Revolution after the left button started to phantom click when it was held down... It was my first time having a Logitech die on me, but just the same, I've
never had a MS mouse die on me.
For as large and clunky as the thing looks, it's really quite comfortable if you have larger hands. For gaming, I find the design pretty damn near perfect. It locks into my hand like a glove and the button positioning is absolutely spot on with some of the best tactile switches I've ever encountered in a mouse. The vertical alignment of the back/forward buttons is something that once you get used to it, you wonder why nobody thought of it before! The change they made from the metal pegs to the flares I can only imagine is an improvement leading that much closer to perfection.
The scroll wheel lacks left/right tilt on this version - which I don't miss. I never used that functionality in games or on the desktop as it was always rather... mushy. I hope the feel doesn't suffer now that they've implemented it, because the scroll wheel on this is one of the best I've come across for gaming. The resistance and detentes are just about right (they could be a bit more concise feeling), and the button aspect is as solid as they come. Never had the wheel slip on me either - the pattern engraved in the metal seems to work pretty dang well, and it doesn't gunk up like the rubber tracks on the scroll wheels that I've dealt with on other mice.
There are some complaints I have with it though. The record macro button is useless on this version, and the on the fly DPI change buttons could use a bit of placement tweaking. I find it too easy to select the wrong DPI in the heat of the moment. It looks like they addressed the size and positioning on the new version though. There's also the weight drawer on this version that I find to have a bit too sloppy of a fit in the mouse, but once again, that doesn't look to be a problem with the redesign.
Finally, there's one caveat with the design that I'll mention since it doesn't appear they changed it much (if at all)... When you look at the profile of the mouse from the side, you can see the mouse starts out elevated near the fingers, then slowly arcs up and peaks around 2/3 of the way through - at which point it does a relatively steep drop off. While the design great for gaming, I find it a bit too aggressive for relaxed every day use. Basically it fits the hand
too well and forces the hand to maintain an active arc. Personally I like to allow my hand to relax and flatten out more for long stretches of loose mouse use. The design will simply not allow that to happen - at least if you plan on actually reaching the wheel or back/forward buttons. To counter this, I've developed a method of holding the mouse rotated a few degrees counterclockwise in my hand when I'm not doing anything intensive, but this obviously is not optimal.
I was planning on upgrading to the X8 when it came out since I rather prefer cordless mice these days. Then the new Kensington trackball got announced, and those plans went on the back-burner.
Still, I plan on picking one up at some point this year.
