I feel petty too but everyone has the freedom to leave, i don't know which other coin is more professional than bitcoin.
Ethereum seems pretty solid from the technical point of view.
But I feel Haern is a whiner, he don't know what he really wants and he had no patience to see how bitcoin could grow big.
I think he would be good in corporate team of researchers with clear goals and deadlines.
Ethereum is definitely solid, but it isn't the Bitcoin killer that it was being made out to be. This was my biggest gripe with the initial hype about Ethereum, was that everyone thought it was going to be so amazing it could destroy Bitcoin's value and draw more of the userbase away from Bitcoin and into Ethereum, but it ended up not really mattering.
Mike Hearn may have left for legitimate reasons, but his whiny demeanour when he made the post about Bitcoin being dead kind of burned a lot of bridges for him.