I've had no problems with break down of my Brooks saddles so far. I am looking at switching to an Imperial from my current Prologo Kappa as I miss the ride I get with Brooks leather. I've had Pro and a B17 with no break down. I'm heavier than you so I am wondering about the cut out in the Imperial and the structural difference. How much proofide or other leather treatment did you use? I never over treated mine as it can soften the leather too much and I avoided getting aggressive with the tension adjustment, also. Your mileage to the break down was pretty short from my experience with Brooks, I'd be interested to see some pictures if you wouldn't mind postings some. A disclaimer, I have not had any perineum pain or saddle sores to date, thankfully.
Bill
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Semper Fi, USMC, 1975-1977
I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13