Are you absolutely sure that .27 has problems with subtitles?
Anyway, I'm generally using 'subcp' option and not 'subfont-encoding' ('subfont-encoding' has not a very encouraging description in mplayer man page).
The most unfortunate thing about your old report was that you reported the problem only...
For SDL sound output it uses SDL internal mixer, so from the performance point of view this is a software mixer. Sound support is not in a very good shape now.
PS. Please don't refer to me as Mr in this forum, it sounds too much business-alike, which is not the kind of communication I would like to have here.