after-tax contributions to 401K - pros/cons?

[simple girl]

Hello!

DH and I (ages 42, 38) have the ability to contribute extra $$ to his 401K with AFTER-TAX $$ (we max out our pre-tax contributions and fully fund both of our Roth's). We are thinking, though, that it might be better to put this extra $$ in our regular taxable account...

Pro's of putting after-tax into 401K are that it will grow tax-free. However, when we take it out, we believe that it will be taxed as ordinary income. We also aren't sure, but believe that our ability to take the $$ out early for FIRE may be hindered (still need to find out the details on this/penalties/etc.).

Putting it into our taxable account means it won't grow tax-free (but we'd put it in a tax-managed account to minimize taxes while it is accumulating). However, when we withdraw funds, it should all be taxed at the lower capital gains tax-rate vs. ordinary income tax rate. Also, we can withdraw the $$$ without any restrictions, which is a big bonus, given we want to FIRE as early as possible.

So, I guess the question is: do the savings achieved via the 401K tax-deferred growth outweigh (1) the savings of being taxed at a lower rate upon withdrawal and (2) the ability to access our $$ easily for FIRE? We think putting the $$ into taxable accounts is the better strategy, but would really like to hear other's thoughts on this.

Thanks,
simple girl