@SuperDave, not sure if this has been asked, but what's the thinking behind the decision to leave to front brake unhidden like other TT/ Aero road bikes? Is it faster this way in your testing?
We did some testing with shrouded brakes like our new DA2 uses. There are some marginal gains to be had but the AR was built around the best balance of low weight, high torsional and drivetrain stiffness, low aerodynamic drag, and a high degree of vertical and cockpit compliance. Building a fork that housed the brake would push the bike weight up over 1100 grams like the Propel. We wanted to keep the AR FRD under 900g during development and keep the fork compliant for-aft.
Using "regular" Shimano brakes on the bike allows the bike to perform in 4 other key categories beyond aerodynamics as well. It freed up development time to focus on taking the ~20g of added drag from the conventional calilper and ~10g of drag from conventional front brake cable routing and saving drag with fork and downtube blend and shape modification.
The AR3 EPS does use a centerpull aero front brake mounted on the front of the bike and for those looking for aerodynamics over pure stopping power or all conditions braking performance there are calipers like the TriRig that'll give back 75% of the drag a Shimano dual pivot brake adds.
I'm running one of our IA brake calipers on the front of my AR1 as I'm typically riding 90 minute parking lot crits, not Alpine descents so giving up a few feet of braking distance doesn't concern me if I can shorten the finish line by a few feet gaining aero performance.