The hack discussed here has served to be robust in two applications for me. 1) using the subject vendor sensors that clamp directly to a pipe and trip open/close on a vary narrow temperature band, and 2) dropping their standard sensor into a freezer to trip upon leaving the critical freeze temperature window. The Zigbee contact switch I've used has also been failsafe as hacked, except for the fact that it is a battery operated solution.
The Senasys sensors are sold into all sorts of applications where things could go very very wrong if they failed. There is no doubt in my mind that they make one to fit any temp band/threshold alert or switching need you have ....but this will not give you an absolute temperature reading.
