On Wednesday, October 23, 2013 9:33:31 PM UTC-6, Nicholas L wrote:
Are some glider designs much safer than others? Or do certain designs put their pilots at risk for certain types of injuries during a crash?

Is there a source for information on this?

The link you posted is from a lecture that is over a decade ago. I think since this time safety cockpits are no longer compulsory and they are a requirement for Certification in most Countries. I disagree with the conclusions drawn in that lecture. I think most pilots, with all other things being equal, would purchase the safer glider.
It is possible, but due to the short gear highly unlikely, that a glider will flip and pin the pilot. This does happen in powered aircraft and roll over protection is provided on the better designs.