Has anyone heard any horror stories about Obenhauf's, or (more likely) experienced shorter saddle lifespans with Obenhauf's compared to Proofide?
My default expectation (null hypothesis) in this case would be no difference.
Do Kiwi paste or Sno-Seal pass your "unknown factor" test? (they may, I'm just not sure how they differ from the unknown factor of Obenhauf's in your analysis)

As for me, I've been riding a Brooks Team Pro for 750 miles and it's still very hard (and I realize it has thicker leather and thus takes longer break-in than the B17) but I loosened the tension bolt slightly which allows for just a bit more flex in the leather, which has improved my riding comfort.