The more I practice with this cube, the better it gets. So this is my final edit on this comment:
The GAN 562 is much better than the Valk5. It turns smoother and faster. It felt like it was catching (mostly it just felt that way) and seemed less accurate, but after I broke it in, it's much better.
After 4 days of practice, I beat all my 5x5 records and that's no surprise. You are on another level with this cube.
The Valk5 turns harder compared to this cube. The GAN is lighter and my hands don't get tired even after an avg50. The bigger my average, the greater the difference between the cubes. The MGC has no chance, of course.
The colors are much better compared to the Valk5. You can see the pieces earlier, so you are faster on average.
The box is nice and not oversized.
The UV coated version may have an advantage because it turns so fast and is so light that you can lose control while turning because of the slippery surface.
This cube definitely turns better than a GAN 3x3 (I don't like new GAN 3x3 cubes, but it feels like one). The normal 3x3 H perm flows with no problems, so it's even suitable for the Roux method, but the only problem I see is the small outer layers. They should be bigger!