I've been using the Edge Expedite Coyote decoy for over a year with mixed results. I can't see that it's hurt any of my hunts when gunning for coyote and I've had quite a few totally focused on it when coming to the call. However, I've also had a few younger coyotes coming to a call and the moment they see the yote decoy, they pop smoke and escape and evade into the woods. I suspect younger ones are more hesitant to approach a larger coyote they don't know. If you want to have any chance of taking a fox on your hunts, leave the yote decoy in the truck. The decoy itself is aggravating as heck to tote to a stand site and the plastic stake that secures it into the ground I ended up replacing with a metal wire yard sign (like those used on campaign signs). I generally start off using it on my first few stands, then get tired to toting it around and toss it in to the bed of the truck for the remainder of the hunt.
Final advice would be to pass on the decoy and get something along the lines of a Foxpro Jack Attack or Mojo Critter. If you do decide to go with a yote decoy, also purchase a kids coonskin cap from Bass Pro and cram it into the yotes open mouth to add realism of a fresh kill.