I test drove an EV6 recently too. It was the RWD Wind without the Tech package. The dealership was great to work with (at least for the test drive). They let me take it out for an extended spin on my own for about 45 min.
For reference, my daily driver is a Model 3 LEMR, and I once briefly owned a 2020 Model Y. (I returned the Model Y due to the pressure/ear pain issue, back when there was a 7-day return policy).
1. As mentioned before, the ride is indeed substantially more quiet and comfortable and the Model 3 or Model Y. The noise/vibration/harshness is clearly superior to a Model 3 or Y. There was no ear pain/pressure/buffeting at all.
2. Handling was similar to Model Y, maybe slightly more agile because it's smaller. Felt well-planted in turns. The tighter turning radius is noticeably better than the Model Y.
3. Acceleration was interesting. It doesn't give you the full torque off the line, no matter how hard you press on the accelerator. Instead, it gives very limited torque for about a second, and then the power suddenly shoots up rapidly. In contrast, if you're already rolling (even really slowly) and mash on the accelerator, you get the full torque immediately. Some YouTube reviews have said that this is specific to the RWD and that the AWD version has immediate, full torque off the line. The salesperson at the dealership said that this is a known issue, and he's hoping this can be improved with a software update someday. Even in its current state, with less acceleration than any Tesla, it's still probably "good enough" for most people. (I very rarely use the full acceleration in my Model 3, but it's nice to have when I need it.) There was no "shudder."
4. I spent a lot of time testing out the Highway Driving Assist (HDA). It's no Autopilot. It "wobbles" slightly back and forth about the center of the lane. It is way more gentle in the amount of turning force it exerts on the steering wheel than Autopilot. As its name implies, it is definitely more of an assist and less of an autosteer. With HDA, I still need to actively steer, whereas with Autopilot, I'd be comfortable resting my hands on the steering wheel while paying attention. It wasn't immediately obvious when it's safe to let HDA do the steering - I had to look for the tiny green icon on the screen. HDA definitely can't handle even the mildly tighter curves that Autopilot takes without problems. On the plus side, when driving in the rightmost lane, it knows to stay to the left at each exit, rather than getting confused as I've seen with other cars with lane-keep assist. The model I test drove didn't have the auto lane change feature - that comes with HDA2, and to get that, you'd have to step up to the GT-line trim.
5. The dynamic cruise control is pretty good. In stop and go traffic, it slows down smoothly and stops closer to the car ahead than Autopilot typically does, which provoked some anxiety at first but is actually much closer to the way I would naturally drive. (I think Autopilot leaves too much space in stop and go traffic.) To start back up again after it stops, I had to tap the accelerator. I didn't find this annoying since I usually end up doing the same with Autopilot. Even though Autopilot will start back up on its own, I find that it waits too long after the car in front has moved forward. I didn't experience any phantom braking (but I haven't had phantom braking issues with the Teslas either - I guess I'm just lucky in that way).
6. As others have reported, the regen is very limited when you first start up the vehicle. I had to pull the right paddle a few times to make it feel like a Tesla (i.e. one-pedal-driving). It reverts to limited regen whenever you turn off the vehicle, so you'd need to do this every time. It's easy, and I think the muscle memory for this would develop quickly.
7. The on/off button feels old-school if you're coming from a Tesla, but I felt like I could re-learn to use it too.
8. It makes a very audible (from the inside) artificial noise when moving. I felt I could live with it.
9. Many people have said that the EV6 has a great interior. But after having driven a Tesla for years, I felt that the interior of the EV6 looked dated and cluttered. It made me appreciate how the Tesla's interior (esp the white one) is so clean and elegant, like a modern spaceship.
10. One thing I noticed about the EV6 is that the rear visibility was surprisingly good, better than trying to see out of that tiny rear window in a Model Y.
11. It has a sizable key fob. I've gotten used to Tesla's phone-as-a-key and I no longer carry any keys in my pocket, and a large key fob would now be annoying.
12. As others have said, the big, clear map on the Tesla MCU is way better than the EV6's.
13. It wasn't as large as I imagined it would be. It felt more like a large hot-hatch than an SUV. The fit and finish was flawless. No panel gap issues. Not a single squeak or rattle.
14. I really liked the ventilated seats. They didn't provide as much airflow as was expecting, but still much better than nothing.
15. The sound system wasn't noticeably better or worse than the Model 3 or Y.
Overall, I think the EV6 is a viable alternative to a Tesla, if it were sold at MSRP with the $7500 tax credit, especially if you don't care much for Autopilot and don't need AWD. Here, the dealership was charging $10K markup plus >$1K of useless add-ons, which makes it very easy to walk away from. Apparently there are plenty of people willing to pay this. (I'm not one of them.)