Keep in mind that ride height is based on volume, so trying to set your height based on a digital gauge can be misleading!
I think they all have around a 10% tolerance on the reading, so between the volume/pressure reading and the tolerance, you can be quite a bit off from one corner to the other...
But the gauges look really cool, and they're a lot simpler than plumbing analogs, so you just need to decide if it's that vital to know exactly what your pressures are!
I've only had one bagged ride that ran gauges out of the 6 I've owned, and that was only because it was on manual valves- you needed the gauge as proof that the car was actually moving up or down!
-Phil at FBI