I don't think accuracy of IMU's out there vary dramatically, and the noise shouldn't matter too much (all major ones within some +-3 db?) -- sure, if they were

I don't think accuracy of IMU's out there vary dramatically, and the noise shouldn't matter too much (all major ones within some +-3 db?) -- sure, if they were a few orders of magnitude more accurate you would get a whole new type of applications -- but with current ranges you're restricted to some kind of pattern recognition (i.e. not full motion tracking), which is quite noise resilient.