Actually, it also allows you to run without an AFM altogether depending on how you set it up.
As far as upgrades go it stands firmly between all other piggybacks and full fledged standalone EMS's. It offers ignition/spark control, fuel control, AFM/MAF translation (run whatever AFM you want on your car), boost control and it can be integrated with an aftermarket wideband (this is useful for a couple thing including mobile tuning and allowing the MAFT Pro to control closed loop AFR instead of the stock ECU.
PS; You can only use boost control if you are running speed/density (AFM deletion setup).