The Oppo + USB drive approach works and can sound very good. There are too many variables to definitively say that either the PC or Oppo approach is better than the other. I use both. For stereo playback I use a PC music server into a Benchmark DAC. For PCM and DSD 5.1 files I use an Oppo 103 with an attached USB drive. The Benchmark system sounds better but it won't play back 5.1 files like the Oppo does.
The downside to the Oppo approach is that the user interface is file/folder based and downright primitive compared to a computer music server with tablet control. Using the latest Oppo tablet app helps, but forget building playlists or searching by artist, album, genre, etc.
Russ