Yeah, I like that site as well. The difference for me, I think, is that a power down doesn't automatically mean they are going to sell to an exchange. It could also mean they need liquidity for an OTC trade or to spread some Steem around to other accounts. The post I mention above about Ned powering down was an interesting case because right before the power down went through, they cancelled it. So it could be a false signal where as a transfer to an exchange is a stronger signal, IMO.