I do have a dedicated home theatre room with room treatment which is only used for movie watching. I currently have an Oppo BDP103 connected via HDMI to a Lexicon MV5 followed by an old (but Solid) Parasound HCA 1206/1000 and Jamo THX ultra II D600 speakers. What are your thoughts on benefits from upgarding to a 105 and running the analouge into the Lexicon? Again just for movie watching only!
It kind of depends on how critical you really are about the details of your audio.
BillP gives a good example of music having more subtle differences compared to movies where you may not notice much difference.
IMHO the BDP-105 should be used in higher-end systems that only use the best speakers, amps, and room treatments and do very critical listening of audio (mostly music).
I don't think anyone would notice a difference with most movies between the -103 and -105. The 103 is no slouch, it still sounds very good with it's analog stage.
IF YOU DO have the passion and time to dedicate to a lot of music, then you should decide if the extra cost is worth it with the -105.
On the flip side of the coin, a quick Googling shows that your MV5 has auto-calibration capabilities for HDMI audio, and that can even make audio sound better too,
it just depends on your overall setup.