The Xenon X uses Pertex Quantum at 36 g/m².
The Strata uses Pertex Microlight at 49 g/m².
The Xenon X has 60 g/m² Primaloft One/Gold.
The Strata has 80 g/m² Alpha (the only available weight at launch).
P1/Gold is, according to my calculations, 2,5 x as warm as Alpha. Plus the fabrics used for Strata are, hopefully, a lot more air-permeable than those used for the Xenon X.