Here is a link to an SWR board thread titled "Defense of Switching." It provides an overview of findings explored in more depth in a number of statistics-oriented threads.
"Our investigations into switching are not meant to encourage frequent trading. What we are looking at is the age-old advice to take a little money off the table (i.e., out of the market) when risks far exceed any upside potential. Our investigations provide some numbers to supplement our own common sense. They help you understand the magnitude and the nature of the risks involved and also how much tolerance there is when you make your own decisions."