Conversions - keeping the shipwreck afloat
I'm not sure there is a single best solution on how to keep information current across a change in format.
In the doc-bound Pharma industry I work for, the biggest overkill I can recall was an complete emulation of a green-screen ERP system after it was replaced by a blue-screen one. It was used, but keeping the old one running as a zombie would have been much easier, as would a transfer of the historical records.
With the demise of mainframes at the end of the last millenium, we made a complete copy of the old central product database* on CD, and as a paper dump. Only the catalogues were ever consulted.
Just in case, we kept a copy of the new database on a laptop, too. This turned out to be one of the better value Y2K ideas, since although it was never used, the programmer who did the port got to keep the laptop once January had faded into history.
A most interesting commercial idea (for Adobe) is to convert everything to PDFs. If you want e-access to the content, you could always scan it in and convert to a current office document, just like today.
I concur with anonymous coward; RTF was never considered for such solutions.
* actually there were two, since we were just mopping up after a merger. Here Y2K was a great help.