ProtoArc sent me an EM11 Pro as part of their tester program, so disclosure out of the way: I received the mouse for free, but these are entirely my own thoughts.
For reference, my hand is roughly 20 x 9.5 cm (length x width).
I used the EM11 Pro for 8+ hours a day at first, mostly for work, and there are actually a lot of things I really like about it. The coating feels nice and comfortable, the main clicks are good and very quiet, the two metal wheels feel great, and both the wheels and side buttons are very well positioned.
The device switcher is probably my favourite feature. Being able to switch devices so easily is something I hadn't seen implemented like this before, and after using it I honestly wish all mice had it. It's such a great feature and the comfort of not having to lift up the mouse to switch device is unparalleled. The dongle storage is also a nice touch, and the mouse feels surprisingly well balanced laterally despite its shape.
Unfortunately, the shape itself just doesn't work very well for me.
The middle of the mouse is quite wide, which keeps my thumb further away from the other fingers than I'd like. Probably due to my thumb being relatively short, I prefer a narrower, more "pinching" grip, closer to something like the Keychron M5. With the EM11 Pro I eventually start getting wrist pain during longer sessions, which is why I ended up switching back to the M5 for most of my daily use.
Even though it wasn't the case for me, the long wrist/palm support will probably be a positive for plenty of people, so I wouldn't take my experience as meaning the mouse is inherently uncomfortable. Hand shape and grip seem particularly important with this one.
A few smaller things I noticed:
- The front gap seems unnecessary to me. Filling that area could potentially improve the forward balance as well, since I occasionally felt the mouse wanted to tip slightly when moving forward.
- The coating feels very nice but picks up skin oils fairly easily, and I'm a little unsure about its long-term durability.
- The main scroll wheel is a bit too easy to accidentally click while scrolling upwards.
- The skates are decent, but I can hear/feel more scratching that I would like on my SteelSeries QcK XXL. Harder surfaces will probably be fine.
- I wish the skates were bigger and more uniform, they are small and sparse which leads me to believe that contributes to the scratchiness. If the front was united, having a single bigger front skate matching the back skate would be a good option.
- I'd like to see higher polling-rate options, even on an office-focused mouse.
- The sensor and lift-off distance are perfectly usable for normal office work, but the tracking could be better for more accuracy-sensitive tasks. If you plan on using this mouse for any kind of precision work and/or gaming, this may not be your best option.
- I also had a few rare connectivity hiccups, mostly over Bluetooth. I have a lot of wireless devices around me, so interference is possible, although this was the only device giving me trouble. Nothing turning it off and on didn't solve, though.
So, bit of a mixed result for my particular hand and grip, but I actually think there's a good mouse underneath that incompatibility. There are several genuinely clever details here, and it's obvious quite a bit of thought went into the design.
If the shape suits you, especially if you like a wider vertical mouse with plenty of palm/wrist support, I can see the EM11 Pro being a very comfortable productivity mouse. I just wish the centre was narrower, because that one change would probably make a massive difference for me.