RE: Dash vs Monero
I don't know whether it was broken or not, but the vulnerability that it presents is like an elephant in the room, it simply cant be ignored. And it will be eventually broken.
Optional privacy sucks as well, because that is optional fungibility, you will have the anonymous coins being 2nd class coins possibly involving criminal activity, while the non-anonymous coins present a framing threat, simply a criminal sending his coins to another person tains the "upstanding citizen" as well with criminal activity.
So it's all bullshit, either all coins are anonymous, in order to protect innocent people from being framed at the cost of letting criminals get away (who can be traced by other means anyway).
Or you have a game of cat and mouse, and non-fungible trash.
Bitcoin suffers from it too, but if this continues the backlog in BTC will be so big that it will be impossible to send any TX anyway, so it will not be affected by this.
Do you really understand how Dash's privacy feature works? For a Private Send to be de-anonymized, someone would have to be in control of thousands of masternodes. The economic cost of pulling this off would are damn near incomprehensible. To say "eventually it will be broken" shows a misunderstanding here. You'd have an easier time just doing a straight up Sybil attack on a PoW chain (Monero included), which would be a hell of a lot more profitable than de-anonymizing a few interesting transactions.