Different times I've seen different reactions. Killed my first bird with a jake and a hen decoy out. He did a real song-and-dance number when he saw them. The next week another bird alarm putted when he saw the same set-up. Went back the next weekend with 2 hens and got him in real close. Then again, I've called 'em in without any decoys at all.

They don't weigh anything. If you don't use them they give you extra padding on your back when setting up.

It all comes down to personal preference.

Romans 8:28