Well, let's not forget that the Oppos also offer many more format playback options. I realize that the OP asked about DVD only. But chances are that he will eventually want to explore the rapidly increasing world of Bluray audio and video. The Sony cannot do this.
Additionally, the Oppos will also allow the playback of DVD-Audio discs, the Sony cannot. And even more: the Oppos will also connect to a home network and/or the internet. This opens up a whole new world of music sources for him to explore. The Sony cannot do this.
And, in the case of the Oppo 105, this unit can operate as a stand-alone, multi-channel DAC that uses the ESS Sabre DAC chips, regarded by many as the best in the world.
Plus Oppo's customer service is head and shoulders above Sony's in terms of responsiveness and overall customer satisfaction. And Oppo are constantly updating even their out of production units with new features and capabilities.
All in all, the Oppos are *much* more versatile machines and will future-proof his system for years to come...
-RW-