The Rainshadow would work well with this. While hiking/backpacking you'll be fine with just a T-shirt and the R2 if you need it. However, if you feel like you might be spending some time hanging out waiting for trains, or hitchhiking, then consider a vest to add to your system. When it's chilly and you're not active, you'll probably want something in addition to keep you warm. A vest will pack down nicely and give you the most warmth per ounce/size as it will keep your core warm. Don't bother with a wind-proof vest - just use your shell as your windproof protection, and something to add 5-10F in warmth even when not active. Check out the Patagonia down sweater vest or the Micropuff vest. For your purposes I recommend the micropuff as it will likely fit better under your rainshadow, and because it'll stay warm even if wet. Wet down is not something you want to drag around with you. Also consider a wool baselayer because it really does resist the inevitable smell. With a baselayer, R2, vest, shell, you can pick and choose which piece(s) to wear for the conditions, and ultimately end up wearing all of them when it's really getting cold. That's the way to keep your pack size down.

I've used the Rain Shadow and R2 on winter summits of 2K meter volcanoes in northern Japan. It will be plenty warm enough for a fall Euro trip.

Have you considered the Marmot Precip?

I think the Rain Shadow and an R2 would be plenty warm. With a capilene/or wool baselayer underneath it would be warm enough to ski in, so I'm sure it would do well enough for a fall Euro trip. The Patagonia Houdini is another cool option. Super, super lightweight, not as wind or waterproof, but it packs down very small and is great for travel