I know the speck says it should be 200ms dependingon signal and device used. I am using a Galaxy S3 and with the controller inches form the Phantom 3, I was seeing about 400ms.

Use a still camera to take a still shot of the phantom watching a stop watch. Have the stop watch and the FPV screenin the same shot and you can compare the time difference between the 2 views of the stop watch.

I would be interested to know if any other devices are getting lower latency.

I dont have the P3 yet but have an I1.

On the I1 the fastest Tablet is the iPad Air2 and the Mini3 followed by the NVidia Shield.