Well, I guess I need to correct myself:

- there actually IS a W in the display, when I have LONG gaps inbetween tracks
- in short gaps (like in vbrfix'ed files), there's no W.

Maybe the longer gaps are related to this one: Beta 11 buffer bugs ... ?
As some of my albums don't have Xing-headers and empeg thinks that some tracks are longer than they actually are, maybe that is the reason why the cache isn't ready when the next song starts...