I've got a little under twenty miles on nanospikes now, in a variety of conditions, and so far pretty nifty. I haven't had any problems with them sliding around on my feet (the sizing is probably more for running shoes than for boots) and when running on ice they have just about zero impact on my form. Better than screw shoes, far better than Yak Trax. On bare pavement, they aren't great but they don't really get in the way; again, far better than the alternatives. In snow that's a little soft they do slide a bit and microspikes would be better if there's the depth. I'm also a little worried about longevity: it doesn't look like the studs would be replaceable. On the plus side, that's only a wear concern, as it doesn't look like they'd tear out.
I think these are definitely the answer for icy running and I suspect they'll be my go-to for shoulder season hiking when the rime can be bad but not thick enough to support microspikes.
I think these are definitely the answer for icy running and I suspect they'll be my go-to for shoulder season hiking when the rime can be bad but not thick enough to support microspikes.