Very interesting reading. I'm quite surprised by how much money the responding authors are getting paid for advances - my understanding is that publishers, in the current climate, are paying smaller advances. For the kind of money being paid out in advances to these guys, their books would have to be selling (to clawback even median rates) very well. My understanding (from talking to successful authors) is that even the larger publishers will generally only print 5 - 10K copies of a debut novel. A successful debut novel would be one which sells 5K copies.
My next novel, FLU, is going out on a UK indie press which has great success in getting their books on the right shelves (Waterstone's, Forbidden Planet etc.). It will see an initial run of 2K copies and my advance reflects that - it's considerably lower than what's highlighted in this article.
Another thing - I don't have an agent. I have no intention of getting an agent, at present, for a number of reasons. One reason is following advice from a major publisher at the World Horror Convention - a good agent may be worth their weight in gold, but a bad agent could literally ruin you. I'm not in the position to know the difference, right now, so I'll keep flying solo.