That is correct 
Tire width selection would depend on what rims i get eventually. From Enveās data, it looks like both the 3.4 and 3.4 AR are pretty evenly matched aerodynamically wise when paired up with the correct tire width.
One consideration for the AR is the very limited number of tires approved to be used on them, plus the GP 5000 TL is specifically called out as not safe to be used on those rims.
I was considering the 4.5 AR too, but I thought aesthetically speaking, the 3.4 would be a better match for my custom steel frame 
If the data is to be trusted, it looks like the difference between the 3.4 AR and 4.5 AR is ~ 1 watt weighted average or roughly 2-3 watts diff at 48kph, 10 degree yaw? If we drag it out to 15 degree yaw, the deeper 4.5 AR starts to break clear of the 3.4AR.