Honestly, I'd expect this cute little baby to put out quite a lot of noise, since it's such a small cooler. I think of gaming laptops.
It's one of those things where you'll feel bad now for not having your part, but you'll probably feel better in the end making the best possible decision. Even if you end up getting a 1070, if you wait you'll have your 1070 with the certainty that it's better than the RX580 (if it's better).
It's kind of like when you're playing a card game like Magic or Hearthstone and you're holding onto a card that kills an enemy monster. "I could kill this annoying little guy who will eventually be a problem... or I could hold out and try to kill a more problematic monster..."