Jason,
I debated this exact topic with Brad Klein a few years back. Here's my take as a supt who overseeded for many years.
For the all-around health of the bermuda turf, not overseeding is best. However, when your course is in AZ or Palm Springs, areas where most play and revenue is in the winter months, not overseeding results in a pretty beat up golf course by Feb/March which just happen to be the months with the most play. Tees really get torn up. The bermuda will not begin to fill back in until May, even June in areas like Tucson. At certain private clubs not overseeding works. But, at a public course doing 4-5K rounds a month in the winter, I don't think you have a choice but to overseed.