I have and I do, vastly. ALSA's software mixer was a terrible hack that you'd be lucky to get to work at all, and then you'd have to take care to have all of your applications request the exact same sample format. ESD was decent in many respects, but still hogged the device from anything that didn't explicitly support it.

Before PulseAudio came along, my "solution" to Linux desktop audio was to simply keep using an ancient sound card that still had a hardware mixer.