The chart you link to pretty much says it all. I've had an Oppo DV-980H for awhile, it was my first upconverting player, and I'm pretty in love with it, especially for the price. These are my non-A/V guy impressions:
The video processing/ PAL to NTSC conversion aren't as up to date and pretty as the DV-983H, but really: it all works pretty beautifully. After hacking, it's handled every disc I've thrown at it (I mean "put in it"), all regions, DVD-Rs, etc. The machine doesn't look too hideous, the remote is cool, and generally it kicks a butt. Did I mention the under $200 thing?
The only problem the 980's given me is that it's fickle about when it chooses to play a disc from the last point stopped. Also load time is not amazing.
There are region-liberation hacks for the 983
(at VideoHelp.com, no less), if you go with that. If I were buying an Oppo today, that's what I'd want. BUT!...
While the 981 outperforms it, the 980's tuff enuf to keep most people happy. Unless there's one of those TVs involved that is bigger than a human body. Given your current output needs, and as the 983 is like, twice as expensive, maybe it's more prudent to go with the 980 and see what the options are when you've made that planned HD jump?