Interesting timing; I just ordered the "standard" Accutire model a few days ago. I needed some other stuff from Amazon.com, so for well under ten bucks with free shipping I figured, "Why not?" I'll let you know how it does compared to my other gauges, if you'd like.
As to the ScanGauge, there's absolutely no question in my mind that it's a worthwhile investment and quality equipment. Plus the developer is readily accessible -- I've been discussing some stuff with him via email.
Maybe it's popular because it's three tools in one, so it appeals to a larger crowd? It's not a full-blown code scanner but it does a fair job. It has the gauge section that's user-configurable, so you can display the four readings
you want. And then there's the trip computer that's so automatic all you have to do is tell it when you fill the tank, and it manages trips (or segments), daily readings, and so on all by itself.
In summary, it's a nicely done, small, versatile piece of equipment that's priced fairly (in my opinion). Not a combination we get to see very often.
Rick