Hi Dave,Ray,Jon,etc
Sorry for the delay in responding but i have been back in the windy and wet UK for a holiday.
Golf marketing men will always offer you the 'holy grail' of golf and the latest gadget to reduce your score by shots.
Just remember one thing,if you do not how far you hit the ball consistently with each club,what is the use in knowing the exact distance?
Your last comment was correct,develop your technique first before resorting to gadgets.
There much cheaper hand held devices on the martket which give you the exact distance using a laser light and these are permitted for use in competitions.
BUT...fix the swing first.
Regards
Mike