Okay some updates for you, the 9 series had a major price cut, I paid less than 250 for my 9590. These CPU's are not long out, and currently only 3 or 4 boards confirm to be compatible. That does not mean they are the only ones, just these are the ones the company's are happy to put there name to without requiring a Bios update.
Not sure why you can not find that information yourself, but none the less here is a link from Asus stating what I quoted earlier.
http://rog.asus.com/261142013/crosshair-motherboards/asus-announces-full-support-for-amd-fx9590-and-...On a final factoid, most of us here who give our time to help do not work for Asus or Amd, and I am pretty sure we get no other perks than a thank you for our efforts. As a result we can not speak in an offical capacity like you are asking, and unless one of the actual Asus paid mods wishes to comment, I expect this may be the best you get on the topic. That does not mean the information we can share is of any less value, and in some cases it is seen as better than the source who has a vested intrest in the product.
You have been given assurances that this combination will work, but if you wish to ignore that and wait, so be it. I know I am enjoying my 9 series CPU and I am sure those who got their hands on multiple CPU's have also.
Hopefully this has resolved your issues?