Two Analog devices ADXL345 Twigs from Seeedstudio arrived today. These offer much better sensitivity than the MMA7660FC Twigs that I have been using. The MMA7660 has a 6 bit 2’s complement output for X,Y & Z acceleration whereas the ADXL has 10 bit resolution in the +-2G range which I would be using.
I have also ordered a couple of MMA8451Q Accelerometer breakout boards from a vendor in China. These have a 14 bit accuracy and have a low noise mode which looks promising. The low noise mode requires a bit more power but for a non mobile application this shouldn’t be an issue.