Like I said, I'm going to personally put this issue to bed until I've done
more reading on it. But I thought it might be worth noting that this
subject has already been a subject of some heated debate elsewhere... which
is not really suprising to me given the paucity of information and the
extent to which IPA is used (at Wikipedia for example).
This is why that perhaps annoying little forum-smiley has been following my
original question around for a few days.
The person responding in the email below seems to suggest keeping things in
the private use domain while waiting for further developments.
(I found this searching for "phonipa" instead of "fonipa".)