Rapha, nice but a bit pricey?

Fit issues : Rain Jacket.

So I ordered 2 sizes, medium and a large. Medium is really snug around chest and armpits but perfect in arms and around the torso. But a merino base layer and jersey makes it quite tight.
Large is more comfy around the shoulders but a bit flappy round the stomach and back.

So whats the fit meant to be? Really snug or a bit flappy/loose? I'd like to know others opinions before I send one back.

I had exactly the same problem with the classic wind jacket... Although I decided to return it for the larger rain jacket over the M/L wind runner.

Wind runner is a great jacket but too flimsy for the unpredictable british weather... Suppose it does what it says on the tin though