I just got off the phone from Wallbike, (i got a saddle cover added to my order)
they said use plastic bags over the saddles in driving rain.
They also said that if you get a saddle drenched (like DH did) to let it dry out before you sit on it.
if you sit on it; you will ruin it.
keep proofhiding it though; this will help.

and no, they can't fix the leather. they can fix any other part of the saddle.
So gals, if you are doing 24 hour rides in the rain, put a plastic bag (or something) over your saddle!