This is part of the problem with Bitcoin and one of the things we have to fix. Too many scams; too much uncertainty. I have a small investment on arbs and have been watching it grow with a gimlet eye. I was kind of thinking they would have a longer run than this, though. I agree with the commenters who say they'll leave BTC in if the site comes back. It won't prove they're honest, but if they are honest, this might encourage them to step up their game.
I'm curious about how much is at stake here. I'd ask everyone reading to post how much BTC or fiat they had sent. Please don't include any 'earnings,' only your principle investment.
Cheers, and luck to all of us.