That is the problem of some sites who are offering a lil bit lower house edge than others. They couldn't maintain the operations or let's say, they can't cope up with the competition. Even though they are offering lower house edge, yet, the sustenance is quite hard especially if you have no sufficient bankroll on hand. So I would say, sometimes it is better to play with known sites even if they are offering like 1%, but you know for sure when it comes to payout, you will have no problem at all.
Actually safedice has been establised for more than 2 years before it turned to like this. At that time, they was running smoothly without any problem from player and there was an user who won more than 100 btc on there (afaik they successfully cashed out). So with that fact i doubt if the reason why they aren't active anymore because of low house edge they offered.