Q:
In customers lab, they have had success (no degradation in performance ) when they eliminate R3 (100Ohms) and short Vin to VinA . 
They would like to know if there is any reason why they cannot do this in production:
- What performance issues does TI think might be compromised?
- Is there any reliability impact that would affect the life of the device?

A:

Shorting VIN to VINA is possible and will not affect the reliability of the TPS63000. In which case, you can also remove the 0.1uF; presuming the 10uF input capacitor is immediately next to the IC. I only recommend this configuration only if the input is a very clean supply, e.g. a battery that does not have heavy and/or frequent load transients that may cause changes to the analog voltage input VINA.
The 100-ohm resistor and 0.1uF capacitor are there to make sure that the internal control circuits are supplied with a stable low noise supply voltage.