Thanks for the advice, especially goonster. I'm commited to the brooks, not so committed to a whole new frame. I feel like I have a very clear idea of what direction to look in now.
I'm not taking Mr. Cranium's condescensions personally. Previous posts have the same tone. Actually, I had his same sentiments on the 200k. I had no idea what kind of culture there was surrounding randonneuring, so I just jumped in with the only geared bike I had and climbed more in one day than I did all winter. There was a large number of race bikes out there. Then on the 300k I invited a city riding buddy and he did the whole thing on his carbon Look with a compact crank and was the 4th finisher!
It's fun to learn all this stuff in such a direct way, by winging it on the road with some best guesses. I got this far so there's obviously more than one way to do it.
Sorry for the digression. I'm off to get a B17!