I've used a Chrony for a long, long time...two of them, actually. The first died and I traded it in about five years ago, and I've been satisfied with them. I have, however, experienced those times when you won't get a reading due to lighting and I have also found that you cannot rely on one if it's any closer to the muzzle than about fifteen feet.
One thing about these things though...you just can't know how accurate they are unless you do a real trial with them. Based on what JB has said, I think I may make a move to a ProChrono.
