I think I read the zigbee devices have a shorter range and use batteries faster (than the wirelesstag.net ones.)
In the lawn I half buried the sensor body in the soil (so it stuck up about 1cm above the soil and was fully buried under the blades of grass) and I had some trouble maintaining a connection to it. (Now it’s under a foot of snow, and not responding, so I can’t find it.). However the other two I own have been rock solid so I’m not yet willing to blame the partial burial for its lack of response. It could be a calibration or quality control issue. The motion and temperature sensors have also been rock solid, with 12 month battery life.
I build an html showing the temperature graph outside my back door : http://ho.hbaspecto.com/WebView/
I’ll measure a tag this evening for you.
User support has been a bit problematic, I think it’s actually just one guy with a couple of staff. I like to support small businesses and since I run one I have some tolerance for individuals just trying to do the best they can. They have been working wonderfully for me.