@jack I appreciate the offer! I'm afraid I'll have to refuse, though, since I can't imagine the e-ink screen would be anything other than a source of frustration.
I feel you're probably right. Right now the smartphone, even as a low-use and emergency device fits well with my average day in a way that the feature phone would probably just cause problems.
I've previously done a bit of research into carrier compatibility and even that was enough to make me doubt the idea. That included support from Punkt. and it was, uh, lacking. Then I just think about the convenience of multiple Apple stores all within relatively easy reach and yeah... I think I'll just wait for the feature phones to get better and for my life to change in such a way that the smartphone is not so valuable.