Did Bill tell you that the B66/72 are sturdier than the B67? Because I have never heard that before ... the difference is really only how they fit on the seat post. We have all three. I ride a B67, although I use a different kind of seat sandwich on it because I am using it on an old-school seat post (Rivendell had it really cheap when I was looking for a new Brooks and I wanted the option of upgrading my seat post). My husband has a new B72for his Schwinn, and I think the B72 is an excellent saddle and if our streets were better I'd have bought one, but I am not sure if it is really any stronger than the B67. Less bouncy, yes, but it doesn't sound like that is your problem.

The saddle my husband broke was an older B72, and obviously we did not know it's history and it had been over-oiled, but it really looked fine and then, bam, the whole nose broke right off ... the leather and part of the metal frame.

What if instead of a B17S you got a Champion Flyer S? If too much of you is hanging off the frame of the saddle, that sounds like you need a narrower saddle? If you got that one you could still have the benefit of the springs. I am looking at the Champion Flyer/Champion Flyer S (not sure which one is right for my narrow butt) for my second commuter.