John:
First let me congratulate you on finding an agent to represent you. This something few people ever achieve. You should feel very proud.
I am one of the very many established authors who don't have an agent. It's not for lack of trying, I've sent out dozens of pitches and attended several conferences. But only one or two have shown even the vaguest interest.
On the other hand, I have had no problem placing three books with solid, paying publishers. None of these involved more than three weeks of waiting.
My new book "A World of Dumplings" (From Countryman Press) is a good example. I sent the pitch to over a dozen agents, and after five dismal responses - including a couple of handwritten notes suggesting I find myself another career - I sent out a batch directly to publishers. I had an offer (which I took) within fifteen days and two more in the following month.
Many months later, I recieved an email from another agent. She wanted to make an appointment with me for a phone conversation. I consider this to be the most positive exchange about a pitch I ever had with an agent. Of course, when she learned the book was sold, she withdrew her offer of a phone call.
My earlier books (all cookbooks dealing with regional, ethnic food) went about the same way; negative responses from agents, quick, postive ones from publishers.
Now, I've got two more pitches going; one already out and the other ready to ship in a few days. I'm still sending them to agents, indeed, they are the gatekeepers for the biggest publishers. But for niche non-fiction writers, they're a luxury, not a necessity.