I have an iPad with True Tone -- I was originally skeptical (the colors aren't accurate!), but subjectively I end up picking up my iPad instead of my phone quite a bit just to avoid the harsh "blue" light. I have no idea what the impact is on my sleep, but it feels like a nice feature to have anyway.
See, that's the problem with red-light reduction software: it seems like it does something nice, but there doesn't seem to be any concrete evidence supporting it other than personal anecdotes of "I can live without this anymore". I haven't seen a study done yet that says "f.lux helps you get better sleep, and not because it makes your phone's colors look horrible".
