I second pretty much everything [MENTION=152773]noglider[/MENTION] shared. Ultimately, for me, you can come up with whatever combo of stuff you think is going to give you your best shot in the wet, but at the end of the day, for me it is all about the feet. If my feet are miserable, I'm probably headed toward miserable. If my feet are pretty good, I don't really care how hard it's raining. It's water. Who cares? At that point, even if it is really coming down, it is just a technical challenge added to the ride. And as pointed out above, unless you live in West Maui or St. Barts or something, sustained extreme downpours just aren't that common. I'm of course excluding severe thunderstorms in, say, Texas or Florida, which no reasonable cyclist should ever be out in. That goes without saying.

I've lived all over the United States and I do believe the people who have the rain best figured out are in fact the Pacific Northwesterners. People in Seattle and Portland just don't let it slow them down. If they did, if they waited for the weather to clear before they went outside to do something, they would never do anything. It rains eight months out of the year! So you pull a hood over your head and carry on. Like I said, it's just water. It's just not that big of a deal.