Spoke with Customer Service atOppo and was told that the 980 is actually a newer model than the 981, regardless of the numbering. The 981 has, of course, the Faroudja processing which Oppo says is better for big screens 46" and up.
The 980 has more options for audio and can be had new for $169 or refurbished (factory option, look brand new) for the paltry sum of $135 if ordered by phone.
I ordered a 980 for use in my 2nd system, but I sure intend to A/B it with my Denon 2900, which is due for replacement soon.