The little Caldwell is fine, within its limits (mainly, the aggravation of having to go forward of the firing line for setup). While I was using mine regularly - I now have a LabRadar - I had no issues with getting readings for rifles, especially if the Caldwell was set up in the shade. I never used the sunscreens or LED light kit. No issue with pistol either, but using a rest became advisable simply to insure rounds went over both sensors (there's another reason - see below).
I still use it for .22 because the LabRadar requires an upcharge for a special microphone to pick up the soft report of rimfire or suppressed firearms, and a buddy of mine who has the microphone had to putter with it to get it to work. There is a learning curve to the LabRadar, but once you understand how to use it, it's an amazing device.
You're probably aware that, if you use a Magnetospeed, attaching the sensor to your barrel will affect point of impact. I saw a very cool idea at the range the other day - a guy with a spigot on his chassis stock attached the sensor to the spigot, not the barrel - presto, POI not affected.
One more thing about using a good rest with your Caldwell. Especially with handguns - it's a Very Good Idea. I can tell you for a fact that a Caldwell can still work with a 9mm bullet hole in it if you miss the sensors and electronics. Due to lighting conditions, I had to put the chrono about 15 feet in front of the firing line. I jerked the trigger of a compact 9mm just enough... the bunny-fart target load rattled around inside the housing a bit and blew the battery apart, with pieces flying out the battery door. Readings are still comparable with the LabRadar, but the tether to the phone app quit working a session or two later.
