I am not sure I follow your logic, but we will be in a similar situation and that is one more reason I have retained my 401k from former employers. I think I agree that once you file for SS it may not be significant but what about the years between 65-67? I would use the worksheet (or TurboTax) to do some what-if exercises to see how it impacts your situation.
If you are Federal employees, can't you roll the IRA into the TSP?
with no reasonable expectation for ER, I'm just here auditing the AP class.Retired 8/1/15.