So we're now back to retail FS2 sound levels, but with more moddability?
Basically, yeah. Modders can now use higher quality sounds (like 32-bit float) as well as control the sound environment (EAX) globally, per mission, and via sexp. Users can make use of those higher quality sounds (including full quality of OGG files which we didn't support before) if they have the hardware for it, or if every bit of memory and CPU cycles really count then they can take advantage of lower quality sound to get just a little bit of extra performance out of the game.
There are some issues with Creative's version of OpenAL which we are hitting against (missing documented features, static-y sound) and that is causing some problems. There is also some sort of issue with the prioritization changes for sounds which is causing important ones to not get played when they should be getting played in place of lower priority sounds.
The main issues that everyone is getting now can be attributed to one or both of those two problems. The first we can't really do much about, aside from telling people who have issues with sound quality to use OpenAL-Soft instead. The priority problem is a code issue on our side, it's just difficult to replicate for testing a fix. There are tweaks that can be made however and some future test builds will hopefully get at least that problem sorted out.