My trusty Logitech M705 Marathon mouse started having a problem with left click. So it was time to replace it. This mouse looks good. But it is almost one inch longer than M705. I have medium sized hands. They are too far away from the front edge of the mouse. So each click takes a bit of extra pressure. It is also noticeably heavier - my hand muscles are a bit sore as I am a heavy user. I think this is because of the Darkfield technology. They need to offer a mouse with the same old technology and rechargeable battery in the same smaller form factor.

This is by far my favorite mouse. I love the way it fits my hand. I feel it is a good ergonomic fit.

Best. mouse. Ever. Best. mouse. Ever. Best. mouse. Ever.

I use the Performance MX with my MacBook Pro and my MacBook Air. It fits my hand well, although I do have large hands. If you have very small hands you may not have a great experience. It is a fairly large device, so if you are looking for small and portable, look elsewhere. The mouse has several programmable options/buttons. I like being able to set some of my Mac options to a specific button (e. g., Launchpad), and I really like the incredibly fast scroll wheel which doubles as a left/right scroll button. A full charge allows the mouse to be used for 8-10 hours a day for about 7 days. The mouse does take up a USB port since it uses a Logitech Unifying device. The only thing that could make this device better IMO is Bluetooth, but that may be a technical limitation.

I really like this mouse. It is responsive and accurate. It feels comfortable in my hand and doesn't get uncomfortable after hours of use. I like how "grippy" it is. The button action is very smooth and require little effort to push. I like the convenience of programmable thumb and side buttons. The only issue I have with the mouse, is that it isn't as accurate on certain surfaces. But that's because I'm coming from an "anywhere" mouse, so take that into account.