Out of the box, my reaction to the MX Ergo was immediately positive. The metal base plate rightly adds heft to a device meant to be stationary and feel solid. The entire bottom of the plate is covered in rubbery grip material, so this thing isn't going anywhere unless you intentionally move it. As always, the wireless performance with the Unifying Receiver was as good as it gets.
The MX Ergo's tracking of a ball itself is also extremely consistent. I suppose that's a natural advantage of getting to choose both the sensor and the tracking "surface" built into the product. When I first got my Elecom EX-G the tracking was miserable. I thought it was because of the mystery wireless solution until I dropped the ball from one of my retired M570s into the EX-G. That solved 90% of my problems, and moving the dongle closer to the trackball solved the rest. I've rolled with an M570 ball in the Elecom ever since. Our own Zak Killian also had problems with one of his Elecom's balls, so this is a thing that's possible to goof up.
Another thing I like about the MX Ergo is that there are 6 points of contact with the ball instead of the traditional three. I'm not 100% sure of Logitech's reasoning for this, but my theory is that the extra points are there to reduce ball jiggle or lift during intense use (don't laugh, this is serious). Coupled with the optional 20° angle, the ball reliably stays in the pocket and tight against the sensor at all times. Admittedly, most people probably wouldn't even notice that this could be a problem in the first place, but since my trackball isn't used on a perfectly level surface, it's something I recognize as a welcome improvement over both the Elecom EX-G and the M570.
Let's briefly discuss gaming on a trackball. I actually used to swear by trackballs for gaming, even for faster-paced games like Team Fortress 2. Nowadays, with gaming mice evolved so far, I no longer peddle trackball gaming with much fervor. I really don't want to get deep into the weeds of DPI settings, cursor speed, or sensor-related nuances, though. This isn't the place for an advanced class on free-spinning either (360 no-scope, pfft). Suffice it to say that you can game quite proficiently with a trackball, but you have to be pretty darn comfortable with them already for it to go well. That said, the extremely low sensor DPI of the MX Ergo makes it even less suited for gaming than either the M570 or Elecom, especially for twitchy shooters. They're great for strategy games though. The more your title of choice looks like a spreadsheet, the better.
Now, before we turn to my list of complaints about the MX Ergo, I've got a small public service announcement to share. If you're not familiar with trackballs, one of their quirks is that, when they are brand new, the ball doesn't move quite as smoothly as it will after a little use. It's a little gross, but let's just say you need a bit of a "slick" to build up on the ball for optimal performance. Think of it as seasoning a cast-iron skillet, or how a too-clean touchscreen can impact your swiping. Yeah.
Anyway, this break-in process usually takes somewhere between a couple hours to a day or so of use in my experience. In addition to this normal trackball idiosyncrasy, the MX Ergo occasionally made a subtle grinding noise and felt noticeably gritty while moving the ball around. I was pretty concerned about this at first, but fortunately it resolved itself after a few additional days of use.
You many have noticed that I didn't so much as give the time of day to Logitech's software suite. You're right, I didn't. Chances are, you can guess what it does and already know if you're going to use it or not.
Almost everything is awesome
Want to hear about that list of complaints? Let's not waste any time. None of these are deal breakers, but they will ultimately stop me short of giving the MX Ergo an unreserved recommendation.
First up are the new back and forward buttons. Since your thumb will be otherwise occupied, the buttons on the MX Ergo are designed to be pressed by your index finger. Compared to the buttons on the M570 and the Elecom, they are, in my opinion, too short, too narrow, and not close enough together. I feel like it takes me more time to press them effectively, while the buttons on the other trackballs are always a twitch and a flick away. It doesn't help matters that the back button is a bit further down on the MX Ergo either. On both the M570 and EX-G, I can position my finger between the buttons and rock back or forward as needed. The MX Ergo requires me to make a more targeted motion that is just plain slower. That may not be a problem for your hand, though.
One complaint I hear leveled against trackballs is that, unlike optical mice, they need to be cleaned. I've always found that to be a silly thing to hold against them, because it takes just a few seconds to de-gunk them. Plus, it only needs to be done a few times a month at most in my experience. I'd say that complaining about cleaning a trackball before you've tried one is like getting squeamish about changing a diaper before you become a parent. You'll get over it quickly. But I digress.
The MX Ergo is no exception to the trackballs-get-nasty rule. Unfortunately, cleaning it is more hassle than it should be. Every trackball I've used since the turn of the millennium has allowed me to remove the ball without requiring any tools. You can usually just poke your pinky finger though a hole in the bottom of the chassis and pop out the ball to get at the detritus. With the MX Ergo, though, unless you have very small fingers, you are going to need to find a pen or other instrument in order to reach the ball. That changes the prospect of cleaning it from "let me just take care of this in a sec" to "oh crud, I forgot to clean this stupid thing before I sat down again." It's pretty annoying to me, but maybe not so much for someone with a stash of right-sized prodding devices at their desk.
Just a couple more nits to pick. The flat orientation of the MX Ergo is essentially useless to me. That's because, when the trackball is flat, the right edge is about one inch above the desk. My pinky naturally rests off the edge of the trackball, leaving it hanging in space without the desk itself to comfortably rest on like it can when the Ergo is in its 20º orientation. I suppose I could craft up some kind of "pinky pillow" with materials I have around the house for some reason, but that seems a bit silly. As with my other complaints, your mileage may vary.
Finally, unless I'm missing a secret compartment somewhere, the MX Ergo is the first wireless input device I've seen in a long time that doesn't include a built-in space to stash its receiver while it's not in use. Especially considering that many of these will be used over Bluetooth, it seems silly to me not to give the user somewhere to keep the receiver tucked away for safe-keeping. Maybe you've already got a drawer full of Unifying Receivers and don't care about a spare, though.