No GPS system is IMO worth the purchase price or fees.
If people were honest they would have to admit that unless they are at least Elite amateur status they cannot have confidence in their ability to consistently hit any club a specific distance.
Most courses I have played in recent years have sufficient markings to enable the club-golfer to select the right club. Whether he or she then hits that club the anticipated distance is another matter.
Not the old GPS v traditional method arguments again. Surely that's for a different thread. Personally I think Sky Caddy are the most accurate GPS which is why I choose to use them and the fees attached. It's a personal choice and I don't like laser devices (not always in the right county off the tee and find GPS better for pointing out the rubbish on the way back to the right hole)