The flex strips are good overall quality, probably closer to a retail grade product than any of the other node options.
I also want to use them for arches and one strip per.
They come inside a pretty nice rubberized sleeve that protects the very thin flex strip and seems to increase the light dispersion a bit.
While they are NOT ideal for wrapping onto an arch, unless your talking about the LED(s) pointing UP, they can be attached sideways onto an arch .... and allow for enough side bending to pull that off, but may require a fair number of zip ties to do properly.
I've been toying around with ways to further enhance the light dispersion while using them. And thus far, the best I have found is using clear tubing I found at Fleet Farm for around $.29 per foot. That was in IA, I haven't found this product in CO yet. The tubing was 9/16 ID and 5/8 OD or something like that. (so thin walled, which was better than thick walled tubing which absorbed too much light). THey require over a 1/2" ID (inside diameter) to fit ... but inside a clear tub does seem to increase the light viewing angles and might also make attaching to an arch a little easier ...