Like you, I rolled some traditional IRA into a Roth IRA, and I deferred SS. Like you said, every situation is different. In my case, I could "fill up" the 15% bracket with a Roth conversion, which was better than waiting to pay 25% later on. You apparently did the same thing with 25% vs. 33%.
So I was just commenting on the good market performance. I actually tried to build a spreadsheet to test this strategy, and that seemed to be a negative.
I agree with mathjak on the " growth of the money in a Roth ..." comparison. Say I'm thinking about rolling $20,000 from a traditional IRA to a Roth IRA. And, suppose I am in a 25% tax bracket.
If I do the rollover, I have $15,000 in my Roth (because I paid $5,000 in taxes). If it doubles before I spend it, then I have $30,000 of spendable cash.
If I don't do the rollover, I have $20,000 in my tIRA. If it doubles before I spend it, I've got $40,000 inside a tIRA. But, in order to spend it, I have to pay $10,000 in taxes, leaving $30,000 of spendable cash. For equal tax rates, this is a wash.
Of course, if my bracket moves up to 33% before I spend the money, the Roth is still $30,000, but the tIRA is only worth $26,667.