The Shootout calibrators (whom I trust more than Cnet or any other publication) didn't see any benefit of the ZT over the VT in a dark room and even recommended the VT as a final result - and the VT does put out an extra 5 ftL or so which can benefit 3D viewing. If one is doing a lot of brighter room viewing, perhaps the filter on the ZT is worth the extra hundreds of dollars. However, I will say the VT60 filter holds blacks very well in a bright room and reflections are no issue at all in a dark room.
Evert time I've seen the VT60 in a bright room and had a chance to compare it with the ZT60 and F8500 it has been obvious that the VT60 doesn't stand a chance against them. Blacks look more like grey in comparison and it is obvious that the ZT60 has the best filter of all three. I still went with the F8500 as no other plasma is even close to match it when it comes to light output, but ZT60 has the most impressive filter, closely followed by the F8500 and with the VT quite a bit behind. After all, the filter is what separates the ZT60 from the VT60, so no surprises there.