So, i've got demoted to Sapphire after trying out Storm Haven and it's full of Runetumors. When I was in Diamond 80% of matches were against Portal and Sword. In Sapphire it's mostly Rune and Haven - both are free wins for the Lamp Dragon I play. Really makes you think who's real tier 1's.
Also, can confirm that you need at least 20 games in Sapphire to a have a promotion. Went 14-6 and got back to the Portal/Sword territory.