Looks very interesting, I might switch from PortAudio to this for my project. But I think I'll wait a bit though, I'm not quite ready to give up on WinXP/Vista support yet.
And as a side note, that is definitely the way to go. WASAPI is a massive improvement over previous windows audio APIs, especially for low latency / pro audio. I'm flabbergasted that some DAWs still don't support it.
[1] https://github.com/andrewrk/libsoundio/wiki/libsoundio-vs-Po...