I am not disagreeing with you here. I have been using tabs and multiple ino files for a couple of years. This particular sketch has been in development for weeks, so getting this strange compile error was a surprise.
Using separate CPP files is likely a better solution than what I have been using, but namespace is something I don't grok. Your 'speakingClock' sketch may be the Rosetta Stone I need.
I suspect that your method may be better because, well here's an example. If I want to use OTA in my sketch, I copy 'ota.ino' to my sketch, then I have to add the declarations and globals to my main sketch. If I am understanding your example, I can do the declarations and global variables in the .cpp and never have to copy them into my main sketch. If I am reading this right, it could make my life easier.