Hello Robert,
The throughput limitation is pretty much a CoreBluetooth BLE limitation and that of the TI BLE Stack. You may be able to squeeze more out of it using some experimental method, but at this stage it is not practical.
My suggestion for the absolute best approach to your sensor reading application would be to use the SensorTag profile as a template. The files are available in the BLE v1.3 folder. You can also visit the SensorTag User Guide wiki for additional information. If your sensor is i2c, then you can simply substitute one of the sensor with the fastest update time with yours. If it is SPI, then you can use the accelerometer service and modify the scan time.
Work with the above example projects and modify your application to match the specifications that are available. Once you get that working, then it will be easier to make modifications to increase the scan rate to the lowest possible rate and still conform to the BLE specs. For additional information on the SensorTag, throughput and BLE specs, do a quick search of the forum, it will prove to be very helpful.
Thanks,
