Your customers are upset and losing faith. Stop trying to defend yourself and take action.
The fact that they didn't help the customer until they took their grievances public indicated to me that either Coinbase don't care about their customers, or they were too busy trying to balance their books because of some proprietary trading gone wrong.
Thus I think it was foolish of Coinbase to release the letter condemning MtGox. Now anything that happens to Coinbase makes them look like total hypocrites. People, glass houses, stones etc.
It's one thing for a magic card trading company to morph into a Bitcoin exchange and have problems... but for a hot-shot start-up in San Francisco with self-proclaimed tech superstars at the helm and millions in the bank to screw up royally, well, it's just embarrassing.