So as I already said yesterday, I seemed to have missed the gamechanging "make-portaudio-work-with-pulseaudio" patch. So I went back, updated the sources and created new packages for the portaudio snapshot of yesterday.
Guess what? It didn't help a bit. simon still crashes seemingly random and nowhere (no backtraces) when you use portaudio and pulseaudio is active.
I give up. There is apparently no real way to have portaudio and pulseaudio coexist together peacfully.
So if you are using pulseaudio (which is the default of Ubuntu and apparently also on Fedora) expect ugly crashes from simon.
The only workaround I could find is to launch simon over padsp and select OSS devices in simon. That seemed to work fine (no crashes there).
Using pasuspender doesn't help at all.
If you do experience a crash due to pulseaudio it is usually bad enough (catastrophic) that it somehow manages to get simond in an infinite loop so you will want to restart that too if simon crashes.
I am sorry for the inconvenience but sadly there is little that I can do within a realistic timeframe. I don't want to get involved into either portaudio nor pulseaudio development so I keep hoping for phonon to develop a recording API.
Maybe for simon 0.3.