I have used a 3d target as a decoy a couple times. The first time the deer did nothing. The second time the deer saw it and turned around and walked right back into the woods. Since then i have never used one again. Mainly because with a 3d target you cant really de-scent it (for lack of a better term). If you think about it, a decoy usually is plastic or rubber which wont hold scent whereas a target is foam, which holds scent without being able to get rid of it.
Now they came out with a decoy that has fur on it or something but i think its a terrible idea because you could never rid of human scent.

Hope this helps.
Tim