Also, say someone converts a bunch of SHNs to FLAC and seeds them. Some time goes by, and other people who already have the SHNs want to convert to this same FLAC set as well. By this time, FLAC has updated to a newer version, so compressing with the newer version will give a different TTH root than the compression with the older version. No problem, sourceforge has old versions of FLAC that can be downloaded and installed, and will yield the same TTH root as compression originally done with the old version of FLAC. Also you can enter the same tags (if they had tags) and replay gain as the old FLAC version.