This experience has taught me to look more carefully at literary agencies.
I was thrilled when Agency #1 asked for a partial, since the drought had been in effect through many, many queries. In the intervening 4 months, I did some more research and found out that agency was more into literary fiction and a little urban fantasy, not epic fantasy (so much for agency guidelines). Then they wrote back, very kindly, with a personalized critique outlining some of the problems they had with the first 50 pages. I felt that the questions they raised were about things that an agent familiar with more sf&f would 'get'. They didn't ask for revisions, and I was a little relieved -- and still grateful for the input.
5 days later, the mms got a small award, in part for some of the same things the first agency found problematic. So I decided this time, I'd better stick with sending queries to agents who 1) had strong backgrounds in sf&f publishing, and 2) had editorial skills, since it was obvious the book would probably need some revision.
Ruthless query rewriting helped, but probably not as much as the new credentials. I picked a really respected agent, whose client list I admire, and tried out the new query. And she asked for a partial.
So I'm back to where I was in January this year, but at least the game has changed a little.