I wasted a lot of time, money, and ammunition with cheap chronographs over the years. Finally bought a CED, and had no problems. But, I was still paranoid, and bought an Oehler, too. I was pleased to find out that all of my set load data, determined on the CED, was confirmed by the Oehler. The CED might be a little more susceptible to low angle, bright sun causing errors. Oehler is constantly getting false readings (ie, reading a random velocity with no shot being fired) when it is below freezing, especially frosty mornings. It also needs a little bit more light. Snow messes with all of them.
For awhile, I had a plywood box for my CED and ran it off of the UV light bar, which gives very consistent readings, and protects it from sun, dust, snow, etc. But that was a pain, especially if I forgot to charge the battery pack.
If you do keep the chrony, you can try a bucket as a replacement screen. I took a white, five gallon bucket, and cut out holes in side so that it would fit over my chrony, and cut out bottom, so I could look/shoot through it. That gave more uniform results, and a friend of mine continued using it for a couple of years after I moved up. We also checked it in line with the CED, and it was pretty close with overhead light, but the more angle there was, the further off it got.
Living up north (Montana) I get a lot of low sun angles, and they seem to be the bane of all chronos, but especially the cheap ones. Even when I use my Oehler, it is on a 2x4 stand with sides so that I can lay a 2' x 4' piece of plywood along side to block the side angle sun in late fall, winter, and early spring.
