I've been pretty happy with my cheap Caldwell chrono. Every once in a while the sun is at the wrong angle for me to get the shades to work and I get crazy high readings (like standard 230gr 45 ACP doing 1300fps from a 3.3" barrel). You might be able to make a better shade for it on those days. Usually I can tilt the chrono to one side or the other to get the sensors shaded on those really bright days.

On low lights days you will just get an error message. Usually one sensor reads the bullet and the other does not. I have only had that happen on days it is darkly overcast or when you are at like sunset. If you get the kit with the IR lights it will fix that problem, but I am rarely shooting when it's that dark out.

80-90% of the time I have no trouble using the chrono. They are typically pretty hard to shoot, though not impossible. At $100 though you could shoot 3-5 of them before you hit the cost of a lab radar or magnetospeed. The few videos I have seen of people using the Lab Radar's it seems like they can be a little tricky to get in the right position to get a reading. With the Magneto Speed I often wonder how that affects the barrel harmonics, so now when load testing you have to choose between shooting for velocities or shooting for groups. I do both at the same time with my Caldwell and it is really easy to know if you have it lined up right to get a reading.