So it's possible to write less than an entire page to flash? I recently got told via private email that I couldn't. Therefore, my Logo Editor does not have the power to write "just" the first four bytes to the logo area of flash (to change the personality without erasing the existing logo).

I don't know anything about how flash is handled, so I don't know whether the two things (what you said and what I was told about the first four bytes) are even actually contradictory or not.