I have lined up my Oehler 35 behind Brian B's and one other persons and they read within 3-4 feet per second of each other and that was just because mine was a little further from the muzzle. When I have tried this with other chronoys, they didn't get very close readings.
Oehlers are the best. Basically, (and I hope this doesn't offend some people) I do not put much stock in any velocity reading that wasn't read from an Oehler. I have found that nine times out of ten, if someone comes to me and gives me a crazy high speed load that is 300 fps faster than what I have gotten with my Oehler, I ask them what chrony they have and it is usually an el cheapo chrony. If someone on here says they were getting such and such velocity and they were using an Oehler, I will not doubt them.
Oehlers also have the widest skyscreens for shade, are made from the toughest polymers, can be set up on a 2,4,or 8' rod for accuracy, and are essentially two chronos in one with the 3 sky screen set up.
The model 43 is a personal ballistics lab containing many more parts and pieces than the 35. You must have a laptop to run it while you are shooting. Check out their website. It is www.Oehlerresearch.com