I do the same thing.Yes; HDMI 5 with Game Low Latency enabled yields an outstandingly low 16-19ms of display lag. As stated in my last post I route 8 HDMI devices through my AVR into HDMI 5 so that I can get that low lag for my Xbox One, Xbox 360 and PS3. It's been said that there's some sacrifice to PQ using HDMI 5 but it looks good to me.
Except on HDMI 5 with GLL enabled, display lag is very bad to horrible on these televisions. From the rtings.com 2014 P-Series review: