Their withdrawal feature is erratic. I can confirm I got "Invalid Address" several times. I hit one that finally worked, but the withdrawal hasn't appeared on the blockchain yet (been about 10 minutes).
But it is true that their green address sees a good number of withdrawals. Seems (again) more like incompetence.
i always pay the network tx fee and when it does go through it is quick...
i swear if BTC fails it is because the people at Gox will bring it down... after all this is all a big experiment at this point