The "TEN" is more costly to operate and way less versatile. It's overkill for decoying ducks. So is a 12 gauge 3 1/2" for that matter. It's good goose and turkey medicine. It's also fine for pass shooting ducks. I like the camo finishes myself. Black synthetic is also fine, I don't think waterfowl can tell the difference between the two! The gloss finishes can spook game sometimes. Just keep it down until you're ready to shoot and you'll be fine.
3" shells are enough for geese. I took a couple geese off Long Lake over by you this fall using 3" BBB's H.V. shells.