El Capitan is the latest Mac OS. The public beta was released today. Yesterday the developer version was released, and prevented Logos from starting up.
I don't know if the public beta released today is the same as the developer beta released yesterday, but I don't want to find out. I spent several hours last night reloading my system.
So, for the time present, don't upgrade to the El Capitan public beta if you truly need Logos for your work (as I do).
Greg Lawhorn