Thank you, Shaun - some very good examples. I've never heard of sensor fusion before, and it seems (compared to increasing the sensitivity of the single sensor to greater degrees) a great way to increase accuracy without dramatically increasing cost. This sensor fusion solution does require a good deal of immediate and local data processing, however. So along with lots of local sensors you'll need lots of local processing. And a local network that can handle the sensor data. (Not sure if that's a lot of bandwidth though - I guess it depends on the frequency of measurements and the number of sensors per network receiver?)