I did a search here and couldn't find any discussions on this topic.
I am doing research on the pros and cons and best practices of Single Page Checkout. Most of the stuff I am finding seems to be from around 2009, when Single Page Checkout was both in vogue and having a backlash. So now that it's 2012, what do people think about Single Page Checkout? In 2009, it seems that the Gap was nearly the only Top 500 retailer using it, how many are using it now? Are there any recent conversion studies (hopefully from large retailers)?
Are there any guides to design/best practices on this topic?
Also I would be interested in any studies on client-side/AJAX error trapping vs conventional server-side error trapping.