I am looking at buying possibly: a KDL-__xbr4 (since as an '07 model it is coming down in price) or one of the new-year z4100-series or w4100's. I notice that the Z's seem to be basically last year's XBR features repackaged (incl. the ACE), while the w's lack the ACE. How much of a difference does it make in practice?

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