I would not expect a big improvement in sound quality. Assuming your are not going to atmos/dtx-x anytime soon or planning on a 4K video upgrade I would stay pat for a while while the Outlaws get the flagship out, which may be a year or so but could be sooner since it shares a lot of the 976 architecture. As is, you are all set for 1080P and the current codecs other than the object based ones and the OPPO is more than capable in that realm.
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Music system
Model 990/7500/Magnepan 1.6 QRs/Technics SL1200 MK2/Aperion S-12 Subwoofer/OWA3/Sony NS75H DVD
APC H15 Power Conditioner

TV System
Large Advent Loudspeakers/ Polk center/Monoprice surrounds/Panasonic Viera 42 inch/Onkyo HT-RC260/Sony BDP S590/Directv


Home Theater System
Onkyo PR-SC886/Outlaw 7125 Klipsch RF-82 L/R,RC-62 center, RB-35 SR/SL, BENQ HT1075, Outlaw LFM1-EX/OPPO BDP-83/Directv
Harmony ONE
Blue Jeans and Monoprice interconnects
APC H15 Power Conditioner