I have had loads of Panasonic plasmas over the years, and the models I've never owned my friends do so I am in the unique position of being able to compare the differences within a home environment.
Neo-PDP isn't that much better than ones without.
Look at a PZ80 against a G10,G20,V10 and you'll notice the black levels are virtually the same. Pansonic admit that NeoPDP panels get lighter after they have been run in so if anyone is going to demo them they need to be looking at one with a good 1,000 hours use on the screen.
If you want black blacks then get one with full Kuro tech which I believe is the V20? IIRC, they are not that much more expensive are they?