There are other things to concider than just the "niceness" of the shotgun.
One being the ease of loading and unloading. You need alot more room to break open a double. If you're crammed into a boat blind or a pit blind with a party of hunters, it becomes a "pain" to load and unload safely. There are, in fact, some who won't let a double in their blinds for safety sake.
Another factor is noise. Now I know you can get long barrels on a double, but the guys i've seen waterfowling with doubles usually have shorter barrels for ease of handling. Let me tell you, you haven't lived until you've had a 12 guage fire a foot from your ears. It hurts bad. I started my son, when he was 8 years old, with a youth model Savage. It's just as bad in the noise department and I've suffered permanent hearing loss from that "little" 20.
On another note, if I were hunting alot of flooded timber, an O/U would be nice. None of what I wrote about above would apply and it would be soooo much easier to maintain.
In respect to waterfowling, I'm alot like Knockemdown, my waterfowling guns get abused hard. I won't take anything out there that I'm going to cry about when it gets scratched or wet. You never know when you might have to use it as a paddle!