I've use decoys on and off over the years and have only drawn in 1.5 year old bucks and fawns. Does seem to become alarmed with the "intruder". Had one 6 pointer come in three times over 2 hours and kept knocking the decoy down. I'd climb down to set it back up and 30 minutes later the buck was back approaching from the rear. Made for an entertaining afternoon sit.
I'm going to focus my decoy aided hunting during the "pre chase" phase this year instead of the rut as once the rut kicks in the shooters are cruising with their noses to the ground and only the young bucks seem to be effected by the decoy.
Good luck. I'm heading out for the first time this weekend with the intent of restocking the freezer with a nice doe or two.