I think trying to jump the gun 7-8 weeks before the release version of Windows 10 and DX12 are even available, would not be a smart thing to do. We need the experts to test out the features that DX12 comes with to make sure these things actually work the way we have been led to believe they will. And once we read the articles showing that, yes, it works as intended, then we can worry about what to get.
You also have to understand that its going to take awhile after Windows 10 comes out before any games will be using it. It is new. So new many of the video drivers for it are still having problems. But every single bug in those will be gone by July 29th... Not!