Sagging Saddles?

It seems that I complain a lot about saddles, finding fault with most of the ones I try if not immediately then certainly within a year's time. This one won't break in, that one hurts my crotch. This one is too narrow, that one is too wide. This one is too soft, that one is too hard... So what now?

Okay, I've had this Brooks B72 for about a year. No complaints about the shape, size or breaking in period - it felt wonderful from the start on a semi-upright bike. I have owned several other B72 models as well - both modern and vintage - and they've all been good. This was the one saddle of all my saddles I thought was pretty darn perfect. Then a couple of months ago I started to notice that the outer edge was pressing into my derriere. At first it was subtle, but the feeling kept getting worse - until one day I looked at the saddle, and the leather was visibly sagging in the center, with the outer edge (where the rivets are) forming a sharp ridge. Regrettably I neglected to take a picture of this before we messed with the tension, but I really ought to have emailed it to Brooks. It is unexpected that a saddle should sag that much under a 125lb rider in less than a year's time. It had never gotten caught in the rain, I am not a proofide zealot, and I had ridden maybe 600 miles on it in the course of 8 months (it is installed on a city bike) when the problem began to present itself.

Though some recommend not to mess with the tension on a Brooks we went ahead and did, and the saddle felt great again... for a couple of weeks. But now, slowly but surely, I am starting to feel the rivets pressing into my behind once more as the leather continues to sag ever so gradually. Darn.

Having spoken to a few long-time Brooks owners and retailers, I do not think that this is an issue with the B72 model specifically, but rather a general issue with quality control and the natural variation in leather thickness. A couple of retailers have told me that some Brooks saddles will sag in this manner and there does not appear to be a pattern to which models are susceptible to it. Well, that's not very reassuring. I am especially disappointed since this particular saddle was my overall favourite before the sagging problem started. I guess perfection is a myth and it is best to keep that in mind to avoid disappointment. I am curious whether others have experienced the "sudden sag" syndrome on any of their leather saddles, and if so which makes and models. Is there a cure?