I don't really care all that much about system sounds (I pretty much always turn them off, as they get annoying after a while). If I can change them easily, and if the sounds aren't too obnoxious, I'd be willing to give it a try, I might actually keep system sounds if they can be done well.
But if you want my opinion, I'd really rather see the resources go to updating and / or improving some of the core applications. The virtual desktops app still needs a fair amount of work (proper wallpaper switching, even if DX is running, multiple monitor support, locking and excluding windows, etc.), a new WindowFX has been promised for a while, it would be nice to see that as well. Not to mention seeing the updated CC and OB. I know these things take a lot of work, and contrary to how it may sound, I'm not really all that impatient, but from the way things seem to go, it makes me wonder if your resources aren't spread a bit thin at times. I'm all for cool new features and applications, but I'm even more for getting the current crop of apps fully ready for prime time.