I purchased the used Soul Chip from the original owner last fall.
To be honest, I would be hard-pressed to say that I noticed that much of a difference. Of course, once you install it you can't easily switch back and forth with it enabled or not to compare.
My initial impressions were that the B mode was slightly more aggressive with the engine braking, but that I couldn't detect any of the "coast" behaviour in D mode at all. Using D mode without Eco on (thus disabling the Soul Chip function according to their documentation) always provided a better coasting ability than with it on, regardless.
During the winter I've been using Eco mode exclusively and when I started using it (with Soul Chip installed) I did notice a noticeable improvement in range vs without. Again, not easy to compare with Soul Chip to without though.
I will need to uninstall the Soul Chip in the spring before I take my Soul in for a battery replacement, so will try to capture updated comparisons then.
At this point, I waver between the whole thing being a scam (it does nothing), vs. it provides some benefit to range. I certainly wouldn't recommend that anyone pay full retail for it.
Maybe I will "open the box" when I remove it to see what's inside...