I've been wearing the Allbirds flats for a few weeks now- very comfortable and softer than I had expected. No rubbing at the heel, and I have narrow heels. There is not much arch support but it would be easy to swap out the insole. One caution is that I downsized a 1/2 size from my wool runners (the flats come in 1/2 sizes)- the fit is pretty snug, but they stretch out a little and I like that they don't slip off easily.
And the new fall colors are really gorgeous!