Not sure why there's so much hang up about his away average, and the fact that there are blokes who've averaged more away from home. Sure, players like Hobbs, Hutton and Sunny have averaged more away than Haydos, but that's hardly surprising given they're also three of the top four or five openers of all time and occupy a plane that Hayden isn't and probably never will be on.
It's using the examples of your Taylors, your Sehwags and, more bafflingly, your Shastris to put down Hayden's status that I don't really understand. Gordon Greenidge averaged 42 away from home, less than any of the examples cited, including Hayden, and yet I daresay his status wouldn't be questioned to the extent Matty's is.
For what it's worth, I'm pretty comfortable with placing Hayden among the top dozen or so Test openers of all time. And more than comfortable giving him a spot in at least an all time Australian 2nd XI, pushing hard for selection in the 1st team.