Your understanding on the make up air situation is not quite correct. The decision as to whether make up air is required is calculated based upon your whole house. More importantly you are missing the point on the hood. The rule of thumb for the size of the CFM that you need for the hood is that you add the BTUs on your stove top and then divide by either 90 or 100, so a 60,000 BTU stove would require a 600-700 CFM hood. Once you know the size of the CFM hood that you need then you can determine if make up air is required. There have been a lot of good post on this website recently about blowers, baffles, duct venting, and silencers.

Maybe it is time for a recap: Blowers (fan blades, motor, housing) have a flow rate that depends on how much restriction is put on their flow. The plot of flow rate versus pressure is called a fan curve. (I've never seen one from VAH, but Broan has them on their web site, and Wolf will supply them if they think you know how to spell 'ventilation.')

I have tried to give VAH the benefit of the doubt when whey claim a real and an equivalent flow rate. What I think they may be saying is that their X-cfm rated blower at zero static pressure will, in concert with their hood, have a flow rate of some portion of X.

This is true of all blowers. But both VAH and the other companies selling blowers in hoods, or blowers alone, actually only have an installed flow rate that corresponds to the point on their fan curve opposite the abscissa pressure value equal to the net pressure drop from fan to the outside and back into the inside and thence to the fan.

Notice that this path includes both the hood and ducting, and the MUA path, which can be passive or active, filtered or unfiltered, formal or open window or house leakage, each combination providing varying amounts of restriction.

The safety issue is that restrictive MUA and high flow rate blowers create a negative pressure in the house that may backdraft combustion appliances, such as gas water heaters. If you have no such devices, nor a fireplace, or your combustion appliances are sealed off from the kitchen and have their own MUA source, then the hazard from negative pressure is removed.

But keep in mind that there is always MUA. If your blower can only move 100 cfm against the restrictions it has to work with, that is both the flow rate from the hood and the MUA flow rate replacing it.

kas