We often talk about the way characters in the novels refer to other characters, usually using a Miss, Mrs., or Mr. title. The use of first names is usually only seen between close relatives or very close friends. It is also a topic that comes up on L&T. So I found it interesting to read that JA refers to some people in a more informal way. In letter #1, she refers to Charles Fowle as Charles and her sister's fiance as Tom (Fowle). In letter #2, she mentions a Warren and a Tom (Chute).
JA refers to other people with titles of respect, so I don't think that she is looking for a shortcut in her writing. It's too early in the read to tell, but I may conclude that some of the formality we see in the novels and the dramatizations is just that, formality -- that wasn't practiced in day-to-day life.