Having gone through some of the head hunter agencies out there, there are good things and bad things associated with them.
Good: They will expose you to non-nuclear jobs that are out there. If you are on the fence about working at a nuke plant or in the nuke world, it might be worth your while to look into what they are offering you. I went with one and got me a cake job doing inspection work(we also like ELTs, hint hint).
Bad: Some are worse than others on this, but from what I saw they seperate O gang and Enlisted guys into two different groups. I got to see the job description that an air force o ganger got and it was basically the job description for a WCS at a factory. I was fully qualified to do the job but I didn't get the chance because I wasn't O gang. I have heard a lot of them do this, which works most of the time except when you deal with enlisted nukes who are over qualified for what we get offered. The other bad thing is that if you go with a company that finds you through the head hunter, some companies will reduce the salary they pay you becuase they have to pay a percentage to the head hunter. So you end up with less money.
I don't know what would be better for a nuke plant, but I do know that I did not interview with one nuke plant when I went to my hiring conference. Did get several offers from non nuke industries.