I have planted both goutweed (by mistake - man was it invasive and jumped all barriers) and the tiarella. Tiarella is a nice well behaved very low ground cover with cute little delicate white plumes, sort of like astilbe in form. It will spread but you can pull up the runners fairly easily. I have one bunch in a place that gets only morning sun and some rain. I dug some and planted it in another spot that needed a low ground cover but gets full sun and needs to be watered. Did it last summer so it will be interesting to see how it does. The snow is gone there and it comes out of the winter nicely green not all beaten up like Arabis for instance.
