I just tried with an iso with the new build and I get the same errors.. I guess they needed to fix 7000 and 1...
I had no trouble upgrading a spare 8.1x64 machine to 10TPx64, and I did it from the mounted .iso on a hard drive partition...no USB, no DVD required. And then just to make sure, I repeated the in-place upgrade of 10TP from the same mounted 10TP .iso that I used to update from 8.1...no problems. (In fact, this is the preferred method of reinstalling because it preserves all of your files & installed programs--method worked in 8/8.1, too, and I just wanted to see if it still applied to the 10TP. It does...)