Color- I think observed color is pretty much a draw, even though it's measurably better on the 8500. Here I'm using more of my experience with my Pro 151 Kuro, when I had it and the Elite at the same time, since I haven't seen the Elite & 8500 side by side. I suspect in rare situations, if you knew what to look for (hello low luminance cyan?), the color might appear more accurate on the 8500- Slight advantage to the 8500.
Black levels-To the naked eye this is also probably a draw in the vast majority of situations, though I haven't seen them both side by side in totally dark environment. The MLL is measurably better on the Elite, but still exceptionally good on the 8500. There might be some rare situations, in a totally dark room with very very dark material where the Elite may have a slight edge- Slight advantage to the Elite.
Sharpness- Also very close based on what I've seen. The 8500 is the first plasma I've seen that has that 'precise' look (for a lack of a better word) not unlike an LED. This one's a draw.
Brightness- For all practical purposes, in a well lit room, this is also really close, but measurably better on the Elite. However, ABL is non-existent on the Elite but not as aggressive as typical plasmas on the 8500. But you will still see occasional instances of the ABL kicking in, it just won't be as frequent or as severe as in other plasmas. Slight advantage Elite.
Motion- I know the knee jerk response here is that plasma is always better. Perhaps I'm not as sensitive to motion issues as some, but I always thought the motion handling on the Elite was excellent. Likewise, I found the motion handling on the 8500 just as good. This one's a draw.
Viewing angle- This one is clear cut, no close calls. Distinct advantage to the 8500.
Carefree viewing- How's that one for a category? Without any concern for IR, burn-in, station logos, tickers etc., the Elite shows the LED advantage. This is not to say that the IR issue can't be managed, it can. Nonetheless, Advantage Elite.
Overall PQ- I know this sounds like a cop out, but I think each one has its virtues. But if there was a gun to my head, based on such an advantage in viewing angle and other performance areas being so close, I suspect the 8500 would appeal to more people.
For me? PLEASE DON'T MAKE ME CHOOSE!!!