Just to share a bit of wisdom without reading the article (because I usually find them useless): Regardless of what Goldman or others may say, I was privy to a cycle phenomenon in the S&P 500 index (SPX) which has correctly called the direction of the index since the 70s (as far as I can verify).
To put it simply, according to the cyles, SPX will begin a new phase (turn) in April, 2015. This means the index will continue in its current direction (up) until 4/2015, meaning every dip is a buying opportunity. Those who leave stocks all together now may miss out on some serious stock gains.
Right now, my mix is 45% stocks (mostly S&P 500 index), 45% bonds, and 10% cash. I haven't varied the mix much in the past few years. I might lessen the stock amounts when Ben lands his helicopter.
My employer has a generous 401k match, so I can stay conservative.