Top positive review
The Bluetooth trackball I'd been waiting for
Reviewed in the United States on September 14, 2017
I've been waiting for this device for well over a decade - a Bluetooth version of Logitech's fabled TrackMan Marble Wheel. And this is, indeed, a really nice trackball for use with new laptops that don't have USB-A ports, such as the MacBook/MacBook Pro.
I'm torn whether to give it four stars or five - it's borderline, and if I could give 4.5, I would. I decided to round up. (And I've gone back and forth several times while writing this review.)
The trackball functionality is exactly as you'd expect if you used the M570, with a few extra features - tiltable scrollwheel, the 'precision' button to allow fine control, and the ability to switch between two devices. The AA battery has been replaced by li-poly and recharges via micro-USB.
The form factor is where things get a little weird. The bottom of the trackball has a 20-degree bend in the middle, and magnets on either side. It ships with a 2mm-thick metal plate that can magnetically attach to either side to cause the tilt. The result feels much more stable than you'd expect, and while you can deliberately tilt it, it's not generally going to accidentally tilt when you aren't expecting it. I find the tilt feels really good, actually - I hadn't expected it to.
The downside of this is that it increases the weight by over 1/3, to over 9 ounces. The device is overall about 4 ounces heavier than the M570. You can use it without the metal plate, but it feels extremely wobbly in that state, and will fall to 'flat' rather than tilted unless propped up.
The only other issue is that there's no spot inside to hold the Unifying Receiver. Not an issue for me because I want this for Bluetooth, but may be an issue for someone.
I purchased the MX Ergo Plus direct from Logitech - the difference is that the Plus ships with an additional plastic wedge that can add another 10 degrees of tilt. If that sounds useful to you, my understanding is that the Plus is exclusive to Logitech and Best Buy.