Sprint is working as fast as possible to upgrade all their towers. But with a lack of people with experience of climbing towers, and building permit authorities taking forever pushing paperwork back and forth, it has really slowed things down.
The Issue I see with Sprint Roll out is Building penetration. Signal attenuation is proportional to the square of the frequency, e.g. if I double the frequency used it actually quadruples the loss of the signal and that's just free space loss. when you account for differences in building penetration on top of that, the loss goes up even more.
To improve in building reception I will need to resort to an LTE Wireless Amplifier Repeater Kit. Something like a -65 dBm to cover the 700/800/1900MHz.