RE: Using a deer decoy during the rut...
No real world experience on this one, but from what I've read, a buck decoy may work the best during the rut to lure in a mature buck. The big boys are very interested in not only the does, but in defending their turf. Again, just what I've read.
Another question about decoys: Anyone ever use your 3-D target? De-scent it, spray some dominant buck urine on him, and you have a decoy... at least I would think you do.