If you look at the news forum you'll see a review posted from CNET Australia on the new Aura. They rate it quite highly whereas they were a bit underwhelmed by the Glo when it was released (they don't have a review for the Aura HD), that alone makes me think the Aura might well be a good choice. The only thing that puts me off is the possible bugs (check out the Fed up with the bugs! poll in the Kobo forum).
As for when you can buy it, due out later this month, and if you check the
Kobo forum, someone in Sweden has ordered from Chapters Indigo in Canada and has a November delivery date. Not sure that's the cheapest way to buy it though.
For me personally, the customer support of Amazon might tip the balance in favour of the PW, but the Aura does look tempting.....