On the positive side with respect to software synthesis, the
Software Dectalk does
work out of the box on Ubuntu --- out of the box that
is if you first install alsa-oss
the ALSA->OSS
compatibility layer.
I've updated the Emacspeak speech server for Software Dectalk to
use alsa-oss
where available; performance is not as
responsive as the Emacspeak Viavoice server using the native ALSA
APIs, but it's a good backup option.