SJM,
To keep the calculation simple, I assumed only one year of delay. So for giving up $12,000 of pre-tax Social Security benefits and $9,450 of after-tax benefits, the engineer would enjoy a lifetime benefit increase of $960 a year. If he delayed for an additional year, he would give up another $12,000 or so and see his benefit increase by another $960 or so. (I say "or so" because there would be an inflation increase to account for.)
If the gain is $960 a year for each $12,000 of benefit foregone, the payback period is 12.5 years. Since that $960 will be inflation-adjusted each year, that's a 100 percent payback in real purchasing power in 12.5 years. The life expectancy of a 62 year old male is 18.9 years so delaying is a much better than even gamble.
Your calculations assume three years of lost benefits but only assume one year of increased benefits.
Here's a link to the column as it appears on the website. Newspapers have been known to make unfortunate cuts. http://assetbuilder.com/blogs/scott_burns/archive/2008/08/13/for-retirement-make-high-probability-bets.aspx
Scott