FWIW, I tried the Slipnots today. I made it from Sixth and I over to the Capital Crescent Trail, then up the trail to Bethesda, then through the Bethesda Streets (Old Georgetown Road and the side streets to my house). By the time I got home, the headlight, tail light, Garmin, etc. were covered in ice. But I never felt even slightly insecure with steering, braking, etc. And I am a complete wimp when it comes to riding in any conditions that are even remotely slippery.
They are a pain to get on in the first place. (I ended up having to deflate my tires to get them on, then inflate the tires again once they were on.) But at least initial indications are that they work.