The ASTM D737 standard on page 3 says, "11.1 Air Permeability, Individual Specimens—Calculate the air permeability of individual specimens using values read directly from the test instrument in SI units as cm3/s/cm2 and in inch-pound units as ft3/min/ft2, rounded to three significant digits.”
Pertex’s response of <3 CFM is the air permeability reading using the ASTM D737 imperial representation and the Montane’s response of 1.0cc max is the equivalent ASTM D737 scientific representation which is 1.97 CFM; they are effectively equivalent values.
15.59 CFM is what I measured for the Microlight fabric used in the Montane Lite-Speed version that Ryan Jordan, Roman Dial, etc. selected for use in the 2006 Artic 1000 trip. The hang tag on the fabric I tested said, “Pertex Microlight E.B.P. Fabric for Body”.
Also in 2006 Pertex sold the company to Japan based Misui. At the time of the sale there were at least 9 Quantum variants and 5 Microlight variants with different weights and air permeability ratings for each one. The Quantum variations offered a smaller air permeability range than the Microlight variations. Your 2012 Pertex Microlight product specification is different than the 2006 variant that I tested.
The ASTM D737 standard tests I conducted, for multiple years of Houdinis, use the same CFM test value representation as Montane and Pertex.