Here is a study, "The Possible `Impossible' Turn" that was done using both student pilots, and experienced pilots, in a simulator. With training, all the pilots with over 100 hours of experience could successfully complete the turnback manoever from 500':
http://web.usna.navy.mil/~dfr/possible.html
While digging that one out of my archives, I found two others of interest.
"The Impossible Turn" is a readable article, arguing the conventional viewpoint, and documenting the physics opposing your safe return to the runway if the engine were to fail shortly after takeoff:
http://www.albertvilleaviation.com/impossible_turn.htm
The other, also titled "The Possible Impossible Turn" is a somewhat more technical article delving into the physics behind the first "The Possible `Impossible' Turn" It recommends a teardrop-shaped return to the runway, flown with a 45 degree bank angle.
http://web.usna.navy.mil/~dfr/aiaa1col.pdf
Centaurus, if you are interested in more studies on the subject, see the cittation list at the end of the third article I cited, and also ask a librarian to help you use a citation index to find later articles that reference "The Possible `Impossible' Turn."