I'm running the FAST XFI on a 496 B engine. In general, EFI gives better fuel distribution compared to a carb or throttle body injection.

Either port or throttle injection can provide drivability benefits. They will self adjust for altitude, temperature and variations in fuel energy (eg gasahol vs straight gas). Also, since you will have pressurized fuel going into the engine compartment vapor lock should not be an issue. The fuel injection setups, especially the XFI type, allow you to run plenty of advance and lean mixtures for efficient cruising and quickly richen things up and pull back the timing when you step on it. Its like having a race carb and economy carb in one package whith plenty of vacuum advance only when you want it.

The XFI setup does require considerable tuning and mapping compared to the self learning types. If you enjoy it that's great or get hooked up with somebody to do it for you. The self learning type is a lot easier.

Another consideration is fuel supply. The fuel injection setups require pressurized fuel from an electric pump. A frame rail mounted pump will work but in tank is better. In tank is quieter, longer lasting and allows you to run the tank lower without wory about cavitation or starving the pump.

I love my XFI setup and have enjoyed tuning it.