The main reason was because of the handeling, and since the handeling got changed a bit a few patches back, it was more easy to find the right setup with an Mercedes since thats a way more balanced car. And i tested to have setups using online with the ferrari setups was a big disatvantage since you need way more downforce on an Ferrari then u eventually need on the rest of the cars. Thats the reason.

this all used to be for the ferrari right? why the change to mercedes?