onkyo has the 4th best rated dvd players on the market for high-end home theater in consumer reports 2002 guide, beaten only by pioneer, panasonic and denon if i remember correctly (I have the DV-SP500, its VERY good.)
I donno about the 300's firmware, but the DV-SP500 is not firmware upgradable so far...I can't find a bios for it, and I can't get any codes from other onkyo players to work correctly on it (one pulls up the bios screen but you can't edit the hex's, its just a view mode.)
I'd avoid it if your ganna use other-than-region1-discs.
The quality, however, is NOTICABLE compared to my friends Apex AD-800, Apex's TOP OF THE LINE Progressive Scan player. If my player using svideo is noticably better at decoding mpeg2 (less artifacts; clearer explosions and anything with brightness or redness, and much deeper blacks) looks better than his using svideo on a simular tv (both panasonics with the same generation tube), I'd bet any onkyo is better than an Apex OR ghettohome player.