That little restriction thru a short 1/2 isn't going to amount to anything, even at 16 cfm or larger, only an issue for 1 inch or larger impact guns. Second, depending on where the regulator is,,, if its before it means even less. there is a bit of advantage with 3/4 line, less friction which does add up over distance, mainly an issue with lower pressures and hi volumes, again in small shop moot, I know a couple got a reg then 50 ft of 3/8 hose, all they ever use, if there are multiple users could just come from reg with a t and another hose.
If this was a 24/7 process and the numbers were significantly higher than these found in home shops then there might be some concerns but at these levels nothing,,, like the difference between 120V and 121 V when you run the toaster a couple times during the day or make a pot of coffee, so minor that the operator can never distinguish the difference and efficiency is negligible especially with a process as inherently in efficient as compressed air tool usage.
While 16 cfm may seem like a lot a 3/8 hose on a large rotary air tool, even a DA sander on a car will run the comp down if ran continuously, its back to where the issue is volume vs losses down the hose, put bigger hose on allows it to empty even faster.
All these concepts are valuable for the general mechanic to understand, lots of the part timers and hobby types I see are excellent craftsman, some better than the average trades guys or "professional" installers but they tend to worry about severe overkill and minor loss issues especially in low duty cycle situations. again this would be a consideration with volumes double this, near 30 cfm on modest length runs and still determined mostly by final hose/whip size and fittings to some extent.
