I picked up the Zen Xtra 40gb a few weeks ago and it plays VBR MP3's just fine. As far as the headphone jack bug, they have apparently fixed it on the latest models, and you can tell by the packaging.
If the packing is heat-sealed around the edges (ie, you have to cut into the plastic to open it and the edges can't be pulled apart), then that is supposed to be the model with the fixed headphone jack.