btce has a solid business model making tons of money by taking a fee on every trade. I wouldnt go as far as saying I trust them, but they have very little incentive to just run off when they make more each year by staying legit. It also couldnt be hard to trace them as they deal with banks. Lastly you most likely arent keeping big deposits with them for a year, Ive never kept money in an exchange for longer than a day.
Contrast that with these mining ponzi's, who's officially stated business would clearly not earn them a dime and actually cost them quite a lot of money, who would make a killing running off at the right moment, whom you have to trust for 6 or more months and who you're not gonna be able to trace in any way if they played their scam right.