I would really like to buy this because that's a fantastic price, but I can't justify spending that much right now. But I don't want you to give it away either.
Over the summer EK released a statement that nickel-plated blocks should not be used with anticorrosion loop additives. Here's a link: http://www.ekwaterblocks.com/index.php?mact=News,cntnt01,detail,0&cntnt01articleid=83&cntnt01returnid=17
Only some blocks were affected, and it seems like it was on an individual basis. If your video card runs fine, then you have nothing to worry about. I guess you could contact PowerColor and ask if other users have reported this problem and if they provide any warranty support. Sorry for the long post; hopefully this was useful.