[VM] Any reason to not use utf-8?

[Yeechang Lee]

I sent a previous message to the list that VM erroneously labeled as
iso-2022-jp. I added

    (setq vm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8))

to .vm, but found during testing that a message containing

áéíóúñ

was labeled by VM as iso-8859-1 and mangled on display in Gmail (but
displayed correctly upon receipt in VM, because I have

    ; First, don't display iso-8859-1 as-is in default face
    (delete "iso-8859-1" vm-mime-default-face-charsets)
    ; Then substitute windows-1252 for iso-8859-1
    (add-to-list 'vm-mime-mule-charset-to-coding-alist '("iso-8859-1" utf-8))
    (add-to-list 'vm-mime-mule-charset-to-coding-alist '("us-ascii" utf-8))

in .vm). I changed the setting to

    (setq vm-coding-system-priorities '(utf-8))

and the next message--labeled as utf-8--displayed correctly in
Gmail.

Is there any reason to *not* use utf-8 as my one and only outgoing
message-coding system?