Holley sniper vs. Edelbrock pro flo

The Holley Sniper is pretty simple... it uses specific sensors to adjust the fuel-air mix: TPS, an O2 sensor and a MAP (manifold pressure sensor) are the main ones supported by engine temp and maybe intake air temp. The FAST is the pretty much the same. With a big cam you can get 2 problems:

• The manifold pressures won't vary in the normal range compared to a 'standard engine" as you go from closed to open throttle. MP's for a big cam are limited to high and higher (low vacuums all around) so while the MAP sensor give readings, you lose a lot of resolution on determining where the engine load is, and so that can limit how many fuel maps the ECU chooses from at a given moment. I would suspect that any setup questions about cam loads a different set of fuel maps into the ECU depending on the general cam size. For a big cam, it would want to load a lot more fuel maps for high manifold pressure (low vacuum) situations, so it can make better choices. Think of it as a finer resolution over a smaller range of MP's.
• The big cam overlap will give erroneous O2 readings at low RPM's where a lot of unburned fuel-air mixture goes straight from intake to exhaust and completely bypasses the cylinder and the burn process. The unburned fuel does not register at all with the O2 senor but the unused oxygen that bypasses the cylinders DOES get seen by the O2 sensor and makes it looks like the engine is burning lean, when it is actually not. So the ECU makes the wrong mixture adjustments. The fuel maps can be adjusted to try to compensate for this but it will only be so good. Once you lose accuracy in the O2 sensor's readings on engine mixture, it becomes a type of educated guessing game.

Any EFI system that has a MAP and O2 sensor will have these possible issues. Using a MAF sensor is an improvement as the ECU can see the actual air flow, not estimate it from the MAP sensor so that is better, but you still have the O2 sensor issues. But MAP sensors are very easy to physically implement and are inexpensive.

OP, the Edelbrock system looks to use the same basic sensors as the Holley sniper system: TPS, MAP and O2, plus a few supporting sensors. It does not look like anything particularly superior in concept. So I would take that info with a grain of salt. But, the details of the implementation are the key; one company may do a better job of putting in maps for low MP situations, and may have better learning strategies.

It is not clear to me why having port injection would make any difference in how the sensors operate or how well the fuel-air maps are set up, selected, or used.