I engaged Pingdom to monitor my home sensor network several years ago when I started to depend on it and found it undependable. The recent upgrades at Pingdom had me looking through downtime stats wherein I found my service to myself to be pretty good:
The persistent downtimes of 2010 were replaced by occasional outages when I converted from Arduino with an Ethernet Shield to Teensy running Txtzyme from an old laptop. Recent failures are all attributed to power failures outlasting my aging laptop battery or Comcast changing my IP address. I'm especially pleased that my foam core and spring clip infrastructure has been serving me well.