John, probably a lot of the extra cost of the XW goes into that extra 10 degrees of FOV. As far as what I've seen in my f6 Dob so far, if the XWs are even better than the XF across a larger FOV, then they must be phenomenal. But even if they are "only" as good, they would still be tops.
Geoff, From most US dealers the XFs are 1/2 the price of the XW within a few dollars, so I'd expect them to be 1/2 the price of the XWs here too.