While the idea seems nice, I'm not sure if it is actually a smart one. By sending your bitcoins to such a site, you are betting against the possibility that they will not get hacked, "hacked", or turn out to be a scam. I'm not sure if taking such a big risk would be worth it for just a ~10 percent annual gain. If the site disappears with all of its users' funds, then you will lose 100 percent of your initial deposit.
Also, doesn't Bter also offer interest for Bitcoin and altcoins as well? I've never heard of all those other sites mentioned in the OP before but I think Bter is quite trustworthy. That doesn't mean they can't get hacked though. And there is still a non-zero percent chance that they could suddenly disappear without a trace. Heck, I remember when they nearly went bankrupt when a hacker made off with 50 million NXT a couple of months ago. It could happen again.
(That being said, I might put a small fraction of my bitcoins into such sites just for fun. But I definitely wouldn't recommend investing all of your bitcoins there.)
I'm sure many people here already know this by now but looking back, it seems that I was right to be cautious since Bter recently lost a large chunk of their users' funds due to an unusual cold wallet hack. What happened to Bter could happen to any other exchange or service that claims to hold/invest your bitcoins - whether it be MyBitcoin, inputs.io, Mt. Gox, or the countless cloud mining/ponzi schemes that pop up everyday, etc. Even if a site claims to offer a positive ROI by paying interest, it's highly likely that the actual expected ROI is negative once the possibility of a hack or scam is accounted for. Moral is; Keep your coins off exchanges people!