2. Prevention of sound card blockade(or take-over) by single application.
The rest like sound card volumes per-app management, one-click sound card mode of operation selection, multiple sound cards management, multimedia streaming over network is very good taken care by pulse. 1&2 would be sufficient for ALSA use on general desktop(not that fancy workstations or people working with several cards etc etc).
Up to the moment - pulse works with everything. It includes both direct output plugins for various, various applications and libraries that this appliacations use. It includes fallback option on catching stream incorrectly directed to alsa.
Oss is a traitor, I will never trust someone turning 180° from BSD to commercial and efficiently abadoning opensource. This is utter crap system. This is the reason ALSA exist. Instead of trolling each other about how bad alsa or pulse is, it is much smarter to separate local problem (fckedup ubuntu because for not reading PA man, from crappy closed sound drivers for several chips, for incorrectly using server kernel on desktop sound server etc) from design flaws. Currently PA has no design flaws. Alsa has two flaws I described, efficiently shifting it from sound system to sound card system. It would be NICE if dmix get the fixes.
<edit package.use to replace "-oss", "alsa" and "pulse" with "oss", "-alsa" and "-pulse" accordingly>
emerge -Cq pulseaudio alsa
layman -a majeru
emerge -q oss
emerge -DN world