That's precisely why I've grown fond of "Rich Text Lite" fields. If you can
manage to control what gets into a rich text field via the Notes client, you
can actually make both sides more-or-less interoperable. Yes, it's going to
tick off the Notes users a bit at first, but once they realise that the big bad
browser won't eat their work anymore, they get over it. If you use RTLFs, you
can manage formatted text, attachments, etc., individually and avoid
browser-proof content altogether. "Dumbing it down", I believe, is what they
call that strategy.