Wow, that is pretty crazy. The eraser is cool, but I don't really even use pencils that much anymore. I have really been loving my Supernote. It kind of gives me the feel of a fountain pen, but it is still digital. I use it pretty much every day.
I rarely use pencils too, so buying that eraser would be a waste. But still, I could see buying it just because it's funny.
I'm still considering the Supernote myself. Actually I've recently started looking at the Boox Palma too. It's too expensive, but the idea of having what is basically an e-ink smartphone has a lot of appeal.
Some of the people I work with are kind of jealous of my Supernote and they asked me to look into something for them. The Kindle Scribe is starting to look like a nice cost effective alternative.