Radonc, you seem to be usually very much in the know about a lot of the programs around the country based on previous posts, but I think you are suprisingly misinformed about Downstate. I'm a med student at Downstate and have rotated through the department and talked to quite a few students/residents in the area about the programs in NYC. Most I have talked to consider the program here one of the strongest in NYC in terms of clinical training, didactics, and atmosphere.
It is true the program is overshadowed by MSKCC (as is every program in NYC) but noone I have spoken to thinks Downstate is overshadowed by other area programs.
I can't argue about the technology issue. Downstate doesn't have some technology found elsewhere, such as a stereotactic radiosurgery system and HDR brachy. But barring those, I think the department is comparable to any other in NYC in terms of technology (save MSKCC again obviously).
And as far as the program being small and having a limited patient base, this is simply far from the truth. Downstate takes 2 residents per year (again more than any other NYC program save MSKCC). And as far as cacthment area, it includes all of Brooklyn, SI, much of Queens, and some of Manhattan (well over 2.5 million people). In terms of hospitals and patients, this gives the residents 5 hospitals to rotate through with in excess of 300 patients seen and treated per year at each hospital. In researching other programs I haven't found many with as many patients being seen and treated in total.
Finally, the residents that I know at the program were all very strong candidates (much stronger than your hypothetical candidate above) when they applied and (for those that didn't genuinely want to come to the program to begin with) were simply limited to NYC geographically.
Sorry if I got a little offended. I just think Downstate gets the short end of the stick in terms of reputation too often, not just in rad onc.
Now, in answer to your original hypothetical, I would probably take the offer outside the match, but I'm no gambling man.