Rapha, nice but a bit pricey?

If its cold enough to need a proper down jacket then its not going to be raining.

Alpkit ones are very good and reasonably priced for proper down: http://www.alpkit.com/shop/cart.php?target=product&product_id=16936&category_id=298

You'd be surprised. Snow (which melts into the jacket), water/snow drips and sweat from inside will also fuck down nice and quickly if you let them.

I'd never put down on over a sweaty layer after exercise. When climbing I usually use a thin Primaloft One layer with a thin down layer over the top of that - the PL1 acts as a barrier to the protect the down and affords warmth, while the down provides more warmth without the bulk of additional PL1. I realise that's not realistic while biking, but still, be careful with down.

Alpkit stuff is indeed very good for the price. Probably much better than the Uniqlo.