sapi voices work fine on wine. I'm using next-up voices over wine. They are commercial though. I didn't manage to install acapela voices, its license manager won't see the trial license so I couldn't try it, but people report it is better.
I spent a day trying to debug the stupid licman with strace to see why it doesn't see the files, but still no luck.
I didn't find a way to read web pages with text aloud so I removed the stupid thing . I use coolreader2 to read books I download.