Which DAC chip are you using? I'd be interested if this is capable of driving speakers like my Creative Stage Air 2.1 soundbar and at least 250 Ohm headphones (like my Beyerdymanics DT990 Edition). To make it perfect, a switch for toggling between Line Out and Headphone Out would be nice, similar to devices like the M-Audio Super DAC.
In general, I would be quite keen on being able to get my hands on a modern soundcard once more which has the capability of adding a wavetable module. Creative removed that aeons ago. It could even breathe new life into my DB50XG card which I still have in a DOXBox setup here (provided it would be compatible with this). I hope a proper case is also planned for this. 😉
1GB flash is probably really a bit excessive. Often bigger soundbanks are not necessarily better than small ones. In fact, the best modules out there like the SC55 or DB50XG managed to produce excellent MIDI music with just 4MB. But it also depends on what you want to do with it - I am talking about MIDI for classic games from the 90s such as Doom, Duke3D or Descent.
If this is really happening, someone will hopefully make a conversion of H. Bredel's 8MBGM Enhanced SF2 soundfont. I would immediately uninstall VirtualMIDISynth after that. But let's not get ahead of ourselves. ^^ Anyway, a very promising project!