I worked in a shop that bought one, and I would say that it's not really worth the investment. Yes, it's a really cool concept and a neat device to have around the pressroom. However, they're pretty touchy and don't allow much room for error. Anybody who's been around press operators knows how many different approaches and techniques there are for setting rollers. With the Digi-Nip everyone has to be using it the same way, which is much more difficult to organize that it should be! Also, it seemed like we needed two people in the unit to get accurate readings and it didn't save as much time as you might think. The strips it uses to actually to get its readings are flimsy and wear out quick. I doubt those are a cheap replacement.
The novelty of it was appealing at first, but it wasn't too long before we were back to setting roller stripes the traditional way. It's just more reliable and really doesn't take that much more time if you know what you're doing.
It's possible I just had a bad experience, though, or received poor training on this.