VistA (a NOSQL solution) is currently the Veterans Administration's EHR for over 160 VA Medical enters and their satellites including Indian Health Service (used in over 50 American Indian Hospitals) and over 200 Department of Defense (DOD) global hospitals.  Over a decade ago current and former VA employees developed the enhancements to VistA paid for by US tax dollars.  Clinicians have become accustomed to its software problems and updates.  The VistA EHR system also has unique modules such as the Traumatic Brain Injury (TBI), Burn Pit Registry, and Embedded Fragments Registry.  These customizations are designed specifically to veterans.  The primary kernel apparently has not been permitted a release update since 1995 and the entire system has been utilizing bug-fix patches.

A recent poll was taken among VistA healthcare technologists.  The question was asked:

What should the VA do about the pending deal with Cerner to overhaul its EHR?

79% responded "Keep VistA and improve the platform", 15% replied "Put the contract out to bid" and the remainder indicated "Sign the contract with Cerner".  

The consensus among the tech community involved with VistA indicates a Commercial Off The Shelf (COTS) solution would not be able to come close to VistA and that the costs would be too wieldy.