If you don't rev match then when you down shift your revs will be higher and as such you'll be fuelling again without having to touch the throttle with your foot.
This is not how modern fuel injected cars work. Fuel consumption is determined by the ECU and is directly proportional (but not linear) to the load required to fulfill the accelerator pedal or maintain idle RPM. When the wheels drive the engine, no fuel is consumed regardless of the RPM.
The only way there won't be an increased load on the powertrain is if the revs are matched. If the revs are mis-matched then the transmission will be at a different point in the powerband (likely out of the powerband) and will result in increased loads experienced.
Right. Perhaps jamesjguthrie isn't seeing the difference between engine noise (mechanical strain), and engine load. "Engine load" is the additional force requested, which will be negative when the wheels are driving the engine. He's also including rev matching in a conversation that is not about clutch or torque converter wear, so there's definitely some confusion.
This is not how modern fuel injected cars work. Fuel consumption is determined by the ECU and is directly proportional (but not linear) to the load required to fulfill the accelerator pedal or maintain idle RPM. When the wheels drive the engine, no fuel is consumed regardless of the RPM.