Here's my Fed III during one of last summer's frog-stranglers:
Hi100% beaver is best, but you can find a tough rabbit hat (IE: Akubra).
Hi JohnnyIf you want the same style of hat that will last, get the Akubra "military"
http://hatsdirect.com/cgi-bin/products.cgi?view=27&returncat=Akubra+Hats&returnpage=1
If not, go for a custom. I have read good things about Jaxonbilt http://www.jaxonbilthats.com/ the rabbit starts at $170 and its custom fit.
My two cents worth.
Johnny
A number of years ago I bought a Borsalino from someone on at this forum. They had bought if for their FIL size 7/8 and the size wasn't quite right. He did me a real service and sold it to me for what he had in it. It was a great hat, soft as a bunny's butt and I wore the hell out of it. Maybe 180 days in a year. Anyway, I had truck trouble and was totally soaked in a downpour. The hat shrunk and I'm not too happy about it. I would normally try to stretch it out, but I like the hat too much to try to fix it myself. Still, nothing beats a great hat in crappy weather.