I have noticed that SPS and coralline grow noticeable faster at high pH vs moderate or low pH. For me, there's no arguing against that. As far as fresh air/CO2 scrubber...I think they can be moderately helpful in most instances, very helpful for some, and not helpful at any measurable level to some. I do use a CO2 scrubber right now, which alone seems to bring my pH up about 0.1 point or so. Been wanting to get a fresh airline, but haven't yet. What really makes the most difference for me, is dosing a very high pH 2 part recipe from Randy using sodium hydroxide. Switching to that from soda ash has brought my pH up from 7.9-8.0 up to 8.3-8.5. That pH jump has caused an increased daily alk consumption from 160ml to 250ml, so just over a 50% increase in consumption. The growth rate is visually noticeable as well, not just a number from a test kit or an increase in alk consumption, but a real noticeable increase in growth.
In short, I think a high pH is very helpful. Fresh air or a CO2 scrubber is one available tool which can aid in getting pH higher, but your results will vary based on your tank/house.