For plasmas, my understanding is that the 981HD's Faroudja chip is not likely to yield macroblock enhancement problems, although you'd want to calibrate the plasma as you would with any player/display combination. That means that I'd be quite comfortable leaning toward a 981HD if you aren't going to add an external scaler. As far as which displays and internal scalers are best, I'm not the one to ask.

I think that the 990's upsample mode may still win out over the 980H's analog output for CD listening (that's the approach I'm using presently, at least), but it's not going to be as wide a margin as existed between the 981HD and the 990. I'll try to get my notes pulled together in the next week or so, maybe even get a few internal pics of the 980H.