One of the main reasons to buy KSG is because of the shield. It was fun using the KSG shield + melee combo before the admins patched it. It felt balanced in my opinion because the melee attack will disable the shield protection for a brief moment.
BAR or PBP + Shield = insanely overpowered and cheap gameplay.
The shield has potential to change the gameplay in iEra. The shield can be drawn out with low freeze but there is a delay before you can shoot after you take out the shield. (like when you take out a gun without reloading it) You can take out the shield the last second before a bullet hits you so that you take less damage. Shooting while holding the shield adds more freeze to your gun like how you shoot the KSG with your shield.