We are actively working through a set of problems with Bluesound related to grouping + playback start. The fixes will ultimately go out in a future version of their firmware–we are not sure when. I think that using WiFi may exacerbate some of these issues, but am not 100% sure.
(@john – please make sure that the scope of the ongoing work with Bluesound covers these topics + that we aren’t missing any opportunities to get stuff fixed here)