I have a Marmot windshirt and was thinking of coupling this with my Integral Designs wind cape. Would this sound like a pretty solid wind/rain set-up? What would be the downsides to this? Total weight is 10 oz. and very compact (very important for it's intended use which is multi day bikepacking).

What are ya'lls thoughts?

What are the materials of both? Are they waterproof?

One of the classic combos for backpacking...but I don't think I'd want to deal with something that flappy on a bike. Frankly, I think I'd try to invest in an eVent bike-specific rain jacket, because even jackets and pants that are fine for backpacking turn into sails on a bike.

FWIW, current killer deal on an eVent cycling jacket:

http://www.realcyclist.com/roadbike/Cutter-Cyclical-eVent-Jacket-Mens/CUT0027M.html

I can't vouch for the jacket, but the reviews on the site look pretty good. 8.9 oz for a large. Recommendation is to size up if you're thinking about layering.

I'm using my Sugoi wind shirt with my Gatewood Cape. I love the combo. I can use my wind shirt with it's DWR for setting up camp in the rain, or in the occurrence or getting cold arms. Works great for me and it's supremely mult-use.