So in summary. Mintcoin has an attack demonstrated against it which proves it is vulnerable.
Blackcoin has suffered no attacks because it is PoS only and no known attacks have been made against the protocol. Yes an exchange was hacked but lots of exchanges get hacked especially bitcoin ones.
wasn't there a hard fork that coincided with people losing a lot of blackcoins or was that just around the same time? I really am curious about what happened as I know the exchange was blamed
from what i remember from the tweets, the update went smooth as silk at mintpal. cr.. that's another story.