I have owned a Pact for about the last five years and it is the most tempermental piece of electronics I have come across. It won't register when used in full sunlight so I have to get to the range before 0800 or after 1700 to get it to read correctly. If it is a cloudy day it will work, but I have to time the shots so the sun is behind the clouds .
At a local pistol match this last weekend one of the range officers had a new Shooting Chrony set up. It seemed to work great for everyone who tried it. I have not owned this particular brand so I can't comment on its long term function.
good luck- oldandslow