Subclass are not name in a natural neither conventional way which makes the code less readable. I recommend that while breaking the API we should rename TplEventText into TplTextEvent and TplChannelText into TplTextChannel.
This work can be found at http://git.collabora.co.uk/?p=user/nicolas/telepathy-logger.git;a=shortlog;h=refs/heads/rename-subclass and is base branch found in bug #33546
I trust sed, so I just did a very quick look. Ship it!