I've written some code (based on Iris Classon's example) to stream accelerometer and gyrometer data from a Microsoft Band to a laptop. I'm using the IBandClient method SensorManager.Accelerometer.StartReadingsAsync() to subscribe to the Band's sensor streams.
Looking at my data, it seems that the accelerometer signal is being clipped at 8 g. Is this the absolute range limit of the sensor, or is there a way to increase the range?

At this time there is no way how to increase range of the sensor. Band SDK does not support changing max Accelerometer data resolution (usually 2/4/8/16 G). I doubt that this will change in the future.