I found a deal on a near new Oehler 35P and got it thinking that, with it, I'd have no lighting issues and errors. WRONG! It works best on cloudy days because direct sunlight and cloudless skies cause the very same difficulties that all the other chronos suffer in those conditions. Further, it's big and bulky and takes up a lot of space....takes time to set up (lots more than smaller chronos)....is costly....and needs a lighting system for low light conditions....just like all the rest.
The benefit of an Oehler is that it times the projectile twice in one pass and calculates the difference between timers and rejects those that show a discrepancy. It's like two separate chronos back to back that talk to one another and if they agree within limits, they validate the results. This increases the confidence of the shooter that his results are true, but little else. For most, a cheaper, smaller, less cumbersome chrono is better even though producing a tad bit less confidence in the results.
If I could set up this Oehler permanently as they do at the range at AoA, I wouldn't own anything else. But if you have to set it up and take it down for every session, I'd choose another. I may never sell my Oehler. But I'd kinda like to have a ProChrono or something similar that I could easily and quickly set up for a short session, and also tear down quickly in the event of an unexpected squall.