And assuming my modifications are correct, here is an odd finding. At 15% tax rate (which I get down to with a 401k) and 15% in retirement, it doesn't matter much what I do:
At stocks=6% for 20 years, Trad=$26619, Roth=$26619, Taxable $26176. The power of compounding doesn't seem to amount to much.
And, frankly, it doesn't matter much where I put my bonds or my stocks:
$28132 stocks tax bonds ira
$27807 stocks roth bonds tax
$28132 stocks tax bonds roth
$27807 stocks ira bonds t
$28357 stocks r bonds ira
So I might as well, just keep all my buckets with the 50/50 asset allocation rather than try to get fancy with optimal asset location:
simply keeping everything at 50/50 is a nice tax-diversified $27,969.
Things change rapidly if my current tax goes up or my after-retirement tax goes up to 25%. The latter is the most probably, as I have a small $13000 pension that will kick in at age 62, and my wife and I each will get $15-23k of SS. So Roth is probably the safest.