No one can (or should) answer your question unless you share your taxable income... this decision all boils down to the tax rate you'll pay today and the tax rate you'll pay if and when you withdraw the money.

But this blog post might be helpful: Are Roth-IRAs and Roth-401(k)s Really a Good Deal?

I posted elsewhere some calculations I did for money that is Roth converted vs not converted.

I calculated at 7% and 10% growth rates and 7 years and 3 years to grow.

If the tax rate is the same at Conversion and withdrawal, the dollar value will be the same.

Surprisingly the same, paying taxes and then growing, or growing and then paying the taxes. You have an disadvantage if the tax rate is higher at withdrawal with non conversion.

I'll go ahead and repost them here.

I ran some more cases and I'm surprised at the results but maybe I shouldn't be.

I'm using what I hope will be my numbers for 2018, ie. 12% tax bracket with a $35,000 Roth conversion.

$35k @12%tax leaves $30,800.

$30,800 @7% for 7 years = $49,458 Roth Tax free dollars.

$35,000 @7% for 7 years = $56,202 taxable. If unconverted.

$56,202 @12% tax leaves $49,458 after taxes. Exactly the same with or without conversion.

$56,202 @20% tax leaves $44,964 after taxes.

Let's try a 10% growth rate.

$35k @12% tax leaves $30,800.

$30,800 @10% for 7 years = $60,020 Roth Tax free dollars.

$35,000 @10% for 7 years = $68,205 taxable. If unconverted.

$68205 @12% tax leaves $60,020 after taxes. Exactly the same with or without conversion.

$68205 @20% tax leaves $54,564 after taxes.

Growth rate makes no difference, Let's try the time frame, I'll drop from 7 years to 3 years.

$35k @12%tax leaves $30,800.

$30,800 @7% for 3 years = $37,731 Roth Tax free dollars.

$35,000 @7% for 3 years = $42,877 taxable. If unconverted.

$42,877 @12% tax leaves $37,732 after taxes. The same with or without conversion.

$42,877 @20% tax leaves $34,302 after taxes.

And again at 10%

$35k @12% tax leaves $30,800.

$30,800 @10% for 3 years = $40,995 Roth Tax free dollars.

$35,000 @10% for 3 years = $46,585 taxable. If unconverted.

$46,585 @12% tax leaves $40,994 after taxes. Exactly the same with or without conversion.

$46,585 @20% tax leaves $37,266 after taxes.

Summary: If you have the same tax bracket at withrawal as when doing the Roth Conversion, the end result is equal dollars, If you have a higher tax bracket at withdrawal, the Roth is a better.

Since I expect to be in a higher tax bracket at withdrawal, I will do a Roth conversion.

I'll lose some deductions as the kids finish college.

The next question, is it worth contributing to my SEP/IRA and doing a Roth conversion?

Advantage, gets more money into tax defered accounts. The SEP/IRA deduction allows more to be put into the Roth Conversion.

Disadvantage, you will have increased RMDs because of the contribution.

You can continue Roth conversions after 70-1/2.

If you have any disagreement, Please post them, I'm here to learn.