I'm in the same boat as you pdcook.
One other thing to consider is that if you choose NDSEG,
Internship restrictions
"Fellows may be allowed to participate in internships at DoD facilities and non-DoD facilities that
are conducting research relevant to the fellow’s program of study. These internships will not be
grounds to request a deferral of the fellowship award. For summer internships, they may be
completed for one or more periods when the fellow's graduate institution does not offer an
appropriate program during the summer months, or when invited by a DoD agency to perform
research. While participating in an internship, the fellow must continue to be academically enrolled
and progressing towards their degree. Internships at non-DoD facilities will require coordination
and prior written approval from the sponsoring DoD agency and the COR."