I received my tire gauge this afternoon and I went right out to see how it worked. In a "nutshell", it worked perfectly (after playing with it a little to learn how best to route the flexible hose and fitting to the valve). I worked from the left (kickstand) side of the bike.
With the bike on the centerstand, I put the front valve stem on the front wheel at the 6 o'clock position. I then threaded the coupling on the end of the hose thru one of the large triangular openings in the rotor so the coupling would come down directly over the valve stem. While squeezing the lever on the coupling, the coupling slid easily onto the valve stem and I pushed the coupling all the way down on the stem. As we all know, there isn't a lot of room in this area to work but, even with my big hands, it was relatively easy.
When I released the lever, the coupling gripped tightly but I could hear an air leak. By again squeezing the lever and moving the coupling around a little on the stem (as per the instructions on the package) I got a tight seal. And then, while holding the gauge in my left hand, I simply pressed the chuck from my compressor onto the fitting on the gauge body and added air while watching the gauge. When the gauge showed the correct reading, I released the chuck and was finished.
For the rear wheel I placed the valve stem at about the 4:30 - 5 o'clock position. In this area there isn't a lot of room between the wheel hub and the top of the valve stem but the hose on the gauge is flexible enought to put the coupling on the valve stem by bending the hose to almost 90 degrees. The coupling made a tight seal on the first try and I filled the tire while holding the gauge in my left hand while pressing the chuck onto the gauge body with my right. Easy!
In anticipation of Paul's problem of not being able to get the fitting on the hose from the gauge to seat/seal properly on the short valve stem, I purchased some valve stem extensions but didn't need them.
I checked both tires with with my old faithful Michelin gauge and found the readings to be virtually identical to the readings from the new gauge so I'm satisfied that the gauge is accurate (at least close enough for government work). I purposely overfilled the rear tire to test the air release feature of the gauge and it worked fine.
Don