Mouse hertz shouldn't matter unless it's 125hz. Stay at either 500 or 1000hz.
If you feel shaky you need another mousepad. Depending on the mouse and the weight/mouse feet size the abundance/lack of friction can contribute to sticky or shaky aim, respectively. I've had many mice and mousepads so I know this issue very well. A mousepad can be great for one mouse, and horrible for another. Same with sensitivity imo.