Regarding the pocket radar ball coach

I think that is what it is called, the one with the blue button, how accurate do you find this to be?

I have one, I like it, but I think you have to be very careful when you line it up. Even a slight tilt downward can seem to reduce the reading by a couple mph.

Very good about showing a reduction of velocity, assuming you are operating it the same, same tilt, same line with the ball etc.

Do the higher end guns have a wider margin for giving accurate readings?

Stalker vs Pocket Radar

Ball coach is very accurate. I have one and compared it with many stalkers. Usually dead on with the stalkers.