I usually make my presentations in beamer as below.
,----
| \begin{frame}
| \frametitle{This is the frametitle}
| \begin{itemize}
| \item Some information
| \begin{itemize}
| \item Some information in a subitem
| \end{itemize}
| \item more information
| \item more information \note[item]{This is a note about this
item}
| \end{itemize}
| \end{frame}
`----
Therefore, I think a simple solution is just writing the \note
command directly
in org that would then be passed to beamer. In org-mode the same
slide would be
,----
| * This is the frametitle
| - Some information
| - Some information in a subitem
| - more information
| - more information \note[item]{This is a note about this item}
`----
This avoids cluttering the org file and since the item (including
the note) will
probably span more then one line, then just leaving notes like this
will allow
hiding everything with the outline capabilities of org-mode. If a
subtree is
used this would probably not be possible.
The "item" option in the note command is used in beamer to number
the notes (I
myself always want this).
Of course that if everyone else like to put the notes at the end of
the frame
then a subtree with all the notes makes sense. Beamer does not
impose where the
notes should be inside the frame and I can reeducate myself to put
them inside a
subtree, but I'd like to leave the notes near the items they are
related to, if
possible.