The most important thing to consider if you plan on only having Coaster Brakes is that should the chain come off -or- should the chain break(snap) while riding down even the slightest of hills, you are gonna get hurt! Other than that, in normal slow speed ( 9 to 12 mph) bicycle riding it really does not matter in 98% of all situations as long as the chain doesn't pop. DO REMEMBER THAT IT CAN BE NEARLY SUICIDAL TO RIDE ANY COASTER BRAKE-ONLY BICYCLE DOWN A STEEP HILL BECAUSE OF THE RISK SHOULD the chain pop off and YOU LOSE THE BRAKES!!!!! In situations where steep hills exist, you may want to Walk The Bike DOWN them!!! It ultimately is your choice but do know the risk....... So yeah, with a Coaster Brake only beach cruiser, you will likely be WALKING YOUR BICYCLE UP STEEP HILLS because pedalling becomes too difficult--------------You will likely also be WALKING YOUR BICYCLE DOWN STEEP HILLS ALSO because of the increased risk of Death should the chain pop off.
I do remember an old ditty from 60+ years ago all of us bicycle riding kids would sing.... "She was comin' down the mountain really fast, she was riding down the mountain super fast, when the chain on her bicycle broke.....
Well, just say it was a sad song about a tragic coaster brake bicycle accident.