Looks like a great bit of kit. Maybe more Spring/Autumn than the Rapha one though? Looks like it might even do winter from some of the photos.
900fp is great - among the best available. But the photos make it look like it probably still has about double the total fill weight of the Rapha jacket. Means it should be a lot warmer but probably also a lot bigger. Also looks like a more robust face fabric, which is again hardier but less packable.
Do you mind putting it on the kitchen scales? And measuring the compressed pack size?
My size Medium Rapha V1 is 236g and a cylinder approx 9cm diameter and 18cm long.