If I am not mistaken--most analysts take the position that your post retirement tax rate will be less than you're present rate.

I don't know about most, but it is not true for a lot of people. For example, barring any unforseen emergency, my pension projection is that I'll be getting more income in retirement than I am getting today, even adjusting for, say, 3%/yr inflation. The same proved to be true for my parents.

I am wondering if this is not the same as a traditional IRA versus ROTH IRA. With the exception of allowable contribution limits.

The same type of analysis would be true for deductable contributions to a Traditional IRA vs. a Roth IRA. ("Traditional IRA" can take either deductable or non-deductable contributions.)

There are differences, however. Generally, besides the larger amount one can contribute to a 401(k) or 403(b) and the fact that such contributions do not reduce what you can contribute to a Roth IRA, there is also creditor protection that a 401(k) enjoys that in many states an IRA (any flavor) does not enjoy.