Bombs and aerial refueling giving a loiter time of 6.5 hours+ is pretty darned good! 
Taking an unbiased look at this is hard for me to do but the
Hoov is definitely capable of handling the stress of the non0carrier environment for another 12,000 hours. It does not require R&D and the purchasing thing is not a factor since it is a government transfer of an asset to a different "department". Safety is also a factor....
the S-3B is a single-engine capable airplane that can take a beating so it beats out the Falson in that respect. It is less of a "beast" than a Herc, and more maneuverable. The only thing that I would not want to see is the Hoov painted White and Orange.

NASA is operating 2 that I know of as icing research testbeds also.