Overview
The first thing you will notice about the M571 is the weight. It ships with all the weights installed and it gives it a nice heft, it feels solid. The overall design is attractive. In addition to the two primary mouse buttons the M571 includes a small third button next to the mouse wheel, which is also a button, and two continently located thumb buttons.
The M571, like the M551, allows you to make on-the-fly sensitivity adjustments with the press of a button, however it is much more subtle than it’s little brother. The button is located between the primary mouse buttons at the top of the curve of the mouse and the indicator is right above it, in the gap between the two buttons.
The weights are stored in the mouse and accessible via a door on the bottom that looks very much like a battery compartment. Once opened see a piece of foam with 4 metal weights sticking out of it. Remove as many as you want to get the weight comfortable. With all 4 the mouse comes in at 164 grams (which is 4 grams heavier than the M551).
Testing
Just like the M551, installation was a breeze. Simply plug the mouse in and wait for Windows to recognize it. The M571 is a very comfortable and ergonomic mouse to use. It is probably one of the more comfortable mice I have come across. It tracks very smoothly on a variety of surfaces such as a cloth mouse pad, wooden desk, and plastic (the cover of a laptop to be exact). The additional weight, while not much more than the M551, is noticeable, and something that I appreciated personally since I like a heavy mouse.
The one problem I ran into with the M571 is that the scroll wheel doesn’t track very well. When scrolling I would frequently find it would either take two “clicks” to do what should be done in one, or the bigger issue, is it would “click back” after I let go of it. For instance, when scrolling through a menu you would expect 1 click in the turning of the wheel to correspond to scrolling one menu choice. However this was not the case. Not only that, but sometimes it would take two clicks and sometimes three. And to make matters even more frustrating it would sometimes actually go back a menu choice once I took my finger off the wheel.