I have been using the Contact crampons ever since the first year they were in production and am very pleased with them, but have only used them on lightweight climbing boots (i.e. Garmont Tower GTX - older version) which have quite a bit of flex, but not as much as trail runners and I have the standard bars. Mine are also not stainless steel, as the current ones. I wonder how well they retain their sharpness with stainless - the longevity of their 'bite' was one thing that always impressed me about these. Mine are also the 'new-matic' version and may not work with trail runners because of a lack of heel lip. Nonetheless, I am intrigued by the idea.
As an aside, I have seen people using Grivel G-10's on softer flexing boots without complaint. I have a pair of G-12's which need sharpening currently, but do have the more appropriate universal strap system for trail runners.
I wish Camp made their Nano-tech version with Sandvick steel on all points, rather than just the front.