eh, it conveys all the advantages of a roth IRA, plus (I believe possibly) stronger bankruptcy protections, (because it's rolled over from a 401K) - so assuming you can contribute to it (which is to say, you have money after maxing your pre-tax 401K) I think that it's a thing you should consider.

Note, I think that maxing out your pre-tax retirement savings first is a good idea because it manages risk well; when you go to withdraw, you pay taxes based on how much you withdraw; If you are rich when you retire, you'll pay a lot of taxes, but that isn't exactly a disaster. If you don't have enough to withdraw a lot, you won't pay a lot of taxes on the other end as-is, and you will have put more in on the other side, so you are net better off. So overall, I agree that pre-tax contributions should be maxed out first, but after that? if you have the opportunity to add another 26K/yr to a roth IRA, and you are making the kind of money where you can swing it, it's probably a good idea.

(Note, I'm no expert. I'd be interested to hear why you think that saving in post-tax accounts is better than saving in roth IRA accounts, if that's what you are suggesting.)