They overlap somehow in that regard, although I wouldn't use them in that capacity.
Sixth Shell and Leading Shot make single fire Tactical Shotguns very potent even at 10 Per. With only those two Perks they become economical, can deal with most of the enemies in the game and are also very consistent. You can use mostly 20p ammo.
AR mostly for Concentrated Fire, Commando and Full Auto. Single Fire at longer ranges won't be anything to write home about, but you will be able to take cover so the added flexibility is much welcomed. Burst fire is where things get interesting as you will be able to eat things like Naga Protectors or soften down crowds of enemies.