Shadowverse has 49.6% winrate going first. That's the percentage I was talking about, the 60% first turn winrate was the August patch which resulted in the current change and the current percentage of 49.6%.
I do not believe Hearthstone has a win rate spread that is as close as that in Constructed but I could be wrong. Of course it's way closer than a 10%, I never said otherwise... but is it closer than a 0.8%? The only statistic we have is from VS and that was from quite a while ago:
http://www.vicioussyndicate.com/going-first-vs-coin-better/
They calculated global advantage of going first as 3.3% but of course it was very dependent on the type of deck you played vs what you played against.