The front canards are fairly new. I put the rear spoiler on several years ago. As far as do they work. I guess so. The technology is pretty simple and it would be surprising if they didn't produce any down force. The rear spoiler is really my attempt at a good looking way to mount a license plate. The fronts are really there to balance the rear.
In all seriousness I do believe that the rear spoiler does generate quite a bit of down force at speeds above 80MPH or so. I admit to not enough track time to really have data. I really not that good anyway.