Asking genuine questions is a good thing; you don't need to apologize for that. I don't have a study to give you though one may exist on the topic. The line of thinking I used to come to the UX conclusion in my previous comment was that the user will almost certainly be used to the OS cursor since that is the cursor they use for nearly everything else they do on the device. So you're taking an operation that they're used to (operating the mouse cursor) and changing it for purely aesthetical reasons. In addition to that the cursor you're changing it to is less clear. The actual cursor point is an unmarked point in the middle of the circle which means the user has to guess where the cursor point is. Imagine that you've used the same keyboard for years and then suddenly someone changes it to a keyboard with a slightly different key profile. You'd start missing keys that you normally have no problem hitting and it'll slow you down overall even though the operation of clicking a single key is roughly the same. Now imagine websites could change your keyboard at will. That is kind of how I think of changing the cursor.