I have the Chrony, the ProChrono, and then got the MagnetoSpeed.
MagnetoSpeed wins hands down. Fast and easy to set up. No worries
about shutting down the firing line to set up. No wind worries. No
light worries. None of the worries accompanied with a regular
chronograph. And speeds are right there with the other two
chronographs, so I have no worries about accuracy, either. It may
well be a little pricey, but with 90% of the hassle of recording
speeds reduced, well worth it. I now use the ProChrono only to
check bullet B.C.'s (and pray for no flyers!).