Don't know them at all, but rosegarden definitely belongs to group. Those 'midi only' things, personally no. Or maybe if they work seamlessly with jack so, that you could use non-daw for audio, and something else for midi?davephillips wrote: Rosegarden http://www.rosegardenmusic.com/
Radium http://users.notam02.no/~kjetism/radium/
ecasound http://nosignal.fi/ecasound/index.php
Frinika http://www.frinika.com/
MusiKernel https://github.com/j3ffhubb/musikernel
SunVox http://www.warmplace.ru/soft/sunvox/
Wired https://sourceforge.net/projects/wired/
Other items such as CabbageHost (http://cabbageaudio.com/) and LNX Studio (http://lnxstudio.sourceforge.net/) could be considered DAWs as well.
Software from the Open Octave project (http://www.openoctave.org/) is apparently the basis for falkTX's Libre Open Octave codebase (https://github.com/falkTX/los), but as far as I know it's a MIDI-only project. The various offspring from seq24 (https://en.wikipedia.org/wiki/Seq24) might also be considered MIDI-only DAWs (if there be such a beast). Helio (http://www.audiopluginsforfree.com/helio-workstation/) is another MIDI-only workstation.
But since many of them are unknow for me, comments of their usability are welcome. At least I don't have time, intrest or energy to evaluate everything. If tool is such that nobody says 'this is great' why should I look at it? There is many marvellous daw's, more than enough studying on them.