My biggest issue with the whole deferred taxes and taking distributions while retired is that I listened to the investment pundits back when Roths were first implemented. The sage advice at the time was if you were over 50 or so it didn't make sense to do Roths and it was best to just keep socking that money in traditional IRAs or 401k. I don't think IRMAA was part of the equation back then and I doubt if it is today for the newer generation of investment pundits. If my current income from SS and pensions is just under $87k and I withdraw enough to put my income just under $163k, I will pay 24% federal tax, 4.63% Colorado state income tax, and 4.45% IRMAA tax for a total of 33% taxes on that $76k distribution. The IRMAA tax calculation (an additional $282/mo in 2022 for Part B and Part D) uses 2020 numbers but will actually use 2022 numbers so they could be different. The moral of this story is do your homework and don't take the pundit's word for it. In future years I will add enough to my RMD to put my income just under $163k for as much income as I can get while in that bracket.
Edit: I left out the Part D surcharge, so Hermit's math is correct. [-]Math check, assuming you are single, but going from just under $87K to just under $163K gives you an IRMAA surcharge of $231.40/month ($376 - $144.60), which is $2776.80 per year, divided by your $76K distribution is 3.65%, not 4.45%. [/-]
I agree with your conclusion, to do your homework and figure out what works for you. I've seen some good advice here on e-r.com that you should defer to any company matching level, and then consider where to put the rest of what you're saving for retirement. Don't automatically defer to the max. That's not the message that most of the public is getting.
Have you looked at whether you saved more than 33% when you deferred the income? It's not as hard to swallow a 33% conversion tax if you saved more than that earlier.
Like Dtail's said after yours, Roth contributions weren't an option for me, and a backdoor Roth would've had a steeper tax rate.
I think people overlook investing in taxable accounts. You'll get hit with some dividend income along the way, hopefully qualified. When you sell, you only get hit with 15% (sometimes 0%) federal + state + the possible IRMAA surcharge but you may be able to control that.
The other thing that some overlook is being aggressive in Roth conversions early. Often people resist, because they can't stomach the thought of paying taxes before they need to, but then get hit with IRMAA and don't like that either.
OTOH, in most cases it probably doesn't make sense to go over the ACA subsidy cliff before 65 just to avoid IRMAA. ACA has these minor (~10%) reduction in subsidy as you approach the cliff, then WHAM! it's all gone. IRMAA cliffs are more like steps. At most you pay a little over $1000 if you go $1 over one of the IRMAA limits.