I'm the one who posted about this on the Microsoft forum. As you can see, no help from them and my email went completely ignored. I don't think they'll be of any help, as this doesn't seem to be widespread enough for them to care.
I did manage to get in contact with somebody at Audio Technica though and explained that I'm having this issue with two AT2020 USB mics across multiple computers, both with Windows 8. I sent the overclock.net link as well, so hopefully it got through that this isn't a faulty mic or a setting that needs to be changed somewhere. In the last email I sent (about a week ago) I asked if he could get this looked into further, as it's obviously going to become a bigger problem as AT2020 users start upgrading to Windows 8. Hopefully that doesn't go ignored as it seems to be the only way that this is going to get resolved.
As of now, the only option I see going forward is to revert back to Windows 7 or get new mics. Either way, it's money down the drain (unless you can get a refund for W8). I upgraded all my computers to Windows 8 though, so that makes things especially frustrating for me.
I'd recommend sending them an email (Audio-Solutions@atus.com) explaining that you are also experiencing this issue, so they at least know that this problem is continuing to grow.