The Benefits of a High Protein Diet
Dietary protein has long been identified as a critical macronutrient to consider in skeletal muscle repair and synthesis. Indeed, resistance trained athletes have advocated high protein diets for many years, therefore let's see what the research says on the matter:
1) Is it harmful? In reality, even intakes up to 3.3g x kg don't have any harmful on blood lipids, liver or renal function. 
Intakes that cover most common 'fitness goals', around ~2.2g x kg seem to be safe. Again according to research.
2) When it comes to bulking and developing muscle mass through a caloric surplus, an intake of 1.6-2.2g x kg of bw is associated with the most gains. 
Exceeding this upper range likely offers no further benefit and simply promotes greater amino acid carabolism & protein oxidation. 
3) When the goal is muscle retention, protein intake needs to be higher in order to prevent. Current evidence based recommendations suggest to keep the intake at 2.3-3.3g x kg of LBM, scaling the intake upwards as you get leaner. 
How high do you like to keep your protein?