Welcome to the site.
Here's a good short video that teaches you exactly how a CVT works. It's covers it all in about 3 mins.
https://www.youtube.com/watch?v=uCEvBGT8twM
I too like the stock variator, didn't see much if any gains from aftermarket.
When it comes to variator weights, compromise is key.
lighter = more take off at top speed expense. Light weight takes longer to move due to centrifugal force, so engine RPM is higher when the buggy starts to move. More take off, or torque if you will. On the top speed side, there is less mass putting pressure on the variator to squeeze the sheaves together forcing the belt to the outside, so you will see less peak speed.
Heavier = sooner take off resulting in lower engine RPM as the buggie starts to move. Less torque if you will. However, the added pressure due to more weight applied to the sheave should force the belt to the outer most part of the sheave resulting in more top speed.
Notice in your pic how the outer most part of your variator is clean? That shows us your belt never really made it to that point. You will achieve maximum speed when you can get your belt all the way to the outer edge. If you're not after top speed, that means nothing.
So ideal variator weight is a balance of bottom end take off, and top speed. All easily adjusted, and ideally tailored to what you're looking for.
I personally like the sliders over rollers. They are slower to engage like a light weight roller, but with more weight for top speed pressure. Not to mention they do last longer. Rollers will flat side as you see in your pics. When that happens, they lose their benefit of fast reacting.
Now rollers are cheaper, so some will buy rollers to find the ideal weight for them. Then they can buy a slider equal to that weight if they decide to go that route. As Opposed to many different slider weights to find the ideal one.
I BELIEVE when choosing sliders you buy them 2 grams heavier than the rollers due to the delay in actuation. Hopefully someone will correct me on this if I'm wrong.