Peek a boo leaves you in no position to counter with gloves up on your fact unless boobing and weaving to get in position is used. Shoulder roll is when used correctly a near unbreakable defense, and with the right on the right cheek and the left hand bent over the midsection you are able to counter fairly easily
if your oppnent is a very fast hard punching southpaw.... dont use the shoulder roll... you run all nite
Unless your mike tyson dont do the peek a boo. advantages if you can do it are you can get inside easily and really pressure and hurt your opponent, disadvantage is if you cant do it as good as tyson you will just end up taking some serious pain while not getting in to let your punches go, shoulder roll is the easier type to practice, the advantages you have are ready to counter punch and dont lose vision with good protection, disadvantages are the shoulder roll wouldnt work against a combo puncher if you werent fast on your feet to get away and would end up just brawling anyway
I wouldn't use either of them so IMO they're both bad.
Okay if you were a expert at both styles (you can never master boxing you just get better in my opinion) what would be the advantages and disadvantages on two styles.