It's not my main, but I bought the Peak S3R because I have too much money and I wanted to try something new. It seems that every manufacturer has a unique feel, and the S3R's feel is hollow, snappy, and a bit blocky. Closest comparison is maybe the GAN 11, but the S3R is more clacky and less smooth.
The S3R is pretty fast and stable too, but I find it has a weird issue at my max turn speed. It's hard to describe, but I think the internal friction is inconsistent, so sometimes it almost feels like the pieces are catching, even though they aren't. The pieces also seem more creaky than in other cubes, which is noticeable with faster and more aggressive turning. The GAN 11 is light and hollow too, but still seems more sturdy. I wonder if this is all due to the S3R's main feature, being able to customize the inner contact surfaces. I'll admit I haven't actually tried swapping the panels yet, so I can't comment on that aspect. But both sets of panels provided with the cube have the same diamond texture, so I'm not sure swapping the panels would change much.
As for the other customization options, there are 3 screw depth options and 2 spring strength options, which are changed by completely swapping out the nuts and springs respectively. The magnet strength can't be adjusted. For a 2021 flagship cube, this is pretty disappointing. That said, I think the factory default settings are perfectly average in a good way. I tried the other options, and still went back to the defaults (medium nuts and weaker springs). If you generally don't stray far from the standard settings, I think you'll be fine with available options on the S3R.
Overall, I wouldn't really recommend the Peak S3R because I think there are better cubes out there. But if you want to try something different, it's pretty good as a speed cube. I don't know anyone who mains the S3R, but I wouldn't be surprised if some people out there really like it.
