Rentz is the one who started this thread, and I'm not sure if he/she is still trying to decide or not. For what its worth, I'll post my experience with both sets:
I reasearched for 3 months before buying a set, and finally decided on the Pioneer over the Panny (after deciding on plasma vs. LCD, but that is another story). The only place I could see them both side by side was at BB with a single crappy feed. Because of the poor feed, it was very hard to tell which was better. I'll be honest and say that a big part of the reason I went with the Pioneer was the bezel.
After receiving my Pioneer (from Invision Displays), all I can say is WOW! Good feeds really give the looking out the window effect. My wife and I were so blown away that we decided to purchase a plasma for my parents. Since we were on the fence between the Pio and the Panny, we decided to get them the Panny. It costed us $717 less, and that is including the sales tax on the Panny (none on the Pioneer since we got it from Invision).
I set the Panny up for them & gave the set the latest firmware updates (1.04 for the tuner and 1.25 for the PQ). The Panny is very very nice, but there is definitely a PQ difference between the two. The Pioneer has much smoother edges and looks more lifelike. The Panny looks great, but it doesn't touch the Pioneer for 'Life-like-ness'. After getting such a great deal on the Panny, I was fully expecting some buyer's remorse for spending the extra $$$ on the Pioneer, but after hooking it up, I see the extra $$$ was well spent.
If you can swing the extra bling for the Pioneer, go for it. You will not be disappointed. OTOH, I'm certain you will be very happy with either set.