There is an interesting book just publisched " Handling the circling " ( the author is a retaired captain ) were is well explained with grafics and mats that , if you are required to be stablized at 3/400 ft with maximum bank of 25 in a circling with minima 600/2400 is impossible to have constant visual reference with the runway .
http://www.aviationcoaching.com/wp-c...ircling5-2.jpg
http://www.aviationcoaching.com/wp-c...ircling1.1.png
(Image from " Handling the circling " book)