my main problem with adding 669 to s3xmodit is that none of the existing s3xmodit trackers (most popularly openMPT, milkytracker, and schism tracker) play back 669 modules correctly, and the only trackers that do only run on DOS. the lyceum says that foobar plays 669 files, but (without having looked into it at all) i question its degree of accuracy in playback, and for voting purposes, playing a module in foobar isn't quite the same as playing it in a tracker.
imo there should be a place for 669 on botb. the official name for the s3xmodit format is "classic DOS module", which 669 modules certainly are, but i have practical concerns about including it and would rather split it into another format. maybe there could be an "obscure DOS module" format as a catch-all for all the other sample-based DOS trackers out there. we could call it farptmtm669etc, which rolls right off the tongue.