EDIT: Not to mention device-specific firmware incompatibilities with newer LTE equipment. A device's modem firmware can only be tweaked to support equipment that exists at the time the firmware is written. If a company releases new LTE base station equipment that does things in a slightly different way, the device firmware may need tweaking. An example of this was one of the changes introduced with the unreleased .901 firmware for the Bionic - it added compatibility for certain Alcatel/Lucent equipment. I suspect that this fix was included in .902 as well, and is the reason why .902 improved things for so many users.