It would be nice if the rotate handle was based on how much the angle between the pivot and the cursor has changed since you started dragging, rather than simply based on the X position of the cursor.
One advantage with this, is that moving the cursor away from the object allows you to fine-tune the angle, more than you can with a fixed rotation rate as you have right now.
The smallest angle I can rotate with now lies at 1.14592 degrees, which is when the cursor has moved one pixel