I have muzzle break on my savage 30-06 and it reduced the recoil by approx 30-40%. It wasn't unbearable but now it is a real pleasure to shoot. If find with mine it doesn't affect accuracy at all.
Also with mine I find that it isn't a huge amount louder just has a different pitch to it now....but ear protection should be worn no matter what gun your shooting.......NO gun is quiet.