That jacket uses
Pertex Endurance fabric. It's water-resistant but not waterproof.
Pertex Shield and
Pertex Shield+ are waterproof and more durable. I have an
Outdoor Research Helium II jacket and
Revel Mitts which are both made from the Pertex Shield+ and it seems great. I am about to replace my sleeping bag with one that has an outer shell made of Pertex Shield as well.
Pertex Shield is 1.66 oz/yd˛, while Pertex Endurance is 0.94 oz/yd˛, so there is a weight benefit to Endurance - the two aforementioned jackets have a 3oz difference (though that would be less with seam taping added to the Luke's jacket). I consider seam taping to be a necessity on either. Luke's also makes a
Pertex Shield jacket that is worth consideration!