Obvious question: what happens if I'm using an old Davis logger, and install this firmware?
Don't know - won't have a chance to try it until tomorrow.
However: I surmise from the lack of warnings posted that there will be no adverse experiences with older loggers. Just my guess of course.
John, I want you to know that I really appreciate your efforts to communicate with us, and to supply us with the best information that you have. You have been
extremely careful to state what you know, and to quote what you have been told, and to identify your thoughts and assumptions.
Occasionally you're going to have incomplete (or slightly misleading) information from Davis. And you (or we or both) will perhaps draw slightly incorrect conclusions. That's not our (collective) fault.
The same is true of people who ask questions of Davis support, and report the answers here.
It appears, from experimental evidence reported here, that there is no major
functional difference between old and new VP2 consoles, nor between old and new loggers. That is, all consoles will accept firmware version 3.12, and with that firmware version, will work with all loggers (including 3rd party loggers). [Yes, I'm aware that the total set of permutations has not yet been reported, so I'm jumping to a conclusion].
Just wanted to emphasize that I'm glad you try to keep us informed.