Both of these work very well. The S9-HD has noticeably better sound (mostly through bass boost technology), more comfortable ear cups and easier to find/press buttons. The only problem I have found with the S9 and S9-HD are that they suffer from occasional 'hiccups' (disruptions in sound) lasting a second or so when used with my HTC Dream (they work fine with my HTC Magic and Backberry Curve, so this seems to be an HTC Dream related problem).
I am able to make/receive calls, play audio and upload my phonebook via Bluetooth with the HTC Dream and Magic. I am unable to send/receive text messages (nor can my Blackberry Curve for that matter, oh well).
This will generate a play list for the music on your phone. This assumes that your music is stored under the Media/Music directory on your SD card and that you are mounting your phone under /media/disk (and you are using Linux!). Tested with the HTC and Meridian players.
find Media/Music -type f | sort | sed 's/^/sdcard\//' > Media/playlist.m3u