OP here with an update on this slightly old thread.
The Terry Fly saddle that I ended up selecting did not fare well at London Edinburgh London. In fact i abandon at 520 miles, just over half way, due to saddle related pain. I had saddle-shaped deep bruising at the, uh, saddle to butt interface. I rode much of the last 100 miles out of the saddle, and towards the end all I could think about was ending the pain. Following my own advice, I didn't quit until I was out of time, but time off the bike wasn't enough to improve the situation.
So it's time to try more saddles.
I picked up a Selle Italia Model X used for $30; it's a little wider and a very different shape. Good reviews. It was decent on a 25 miler today, with my butt still a little tender from LEL, but that's no real test. I'm riding a 200k next weekend so we'll see then.
I have a 1000k on the schedule in a few weeks. If nothing better comes along, I'll throw my original saddle back on - a Sella Anatomica. I did finish a 1200 on it, though but that was so painful it kicked off this whole saddle search.
I have noted all the suggested saddles in this thread, I'm just not rich enough to buy them all.