Well I have finally sat down and listed to the LG V20 v G6. Interesting. I am in high impedance mode into Audeze Sine headphones. High impedance is triggered by a cable with 470 ohms to ground plugged in first, then headphones.
I took a while to get another 3.5mm splitter to build in some resistors as my adapter to kick it into high impedance mode. My last two got broken by getting caught on others on the subway as they walk off. So this time I made two so I had a back up. This allows me to plug one in each phone, keeping them in high impedance mode and playing, at the same volume level. Swapping between then is now a matter of plugging in.
I am not hearing a lack of bass on the G6 as previously stated. But the slightly crisper treble and upper mid does in my experience have the effect of tilting the balance towards the top end, so this can be the interpretation people will have. This comes across as slightly better transients, cymbals, snare etc. The bass if anything is tighter on the G6. The general impression is that the G6 is less cluttered when the music gets busy, while the V20 sounds (great, but) can get very slightly less clear. This has the effect of making the V20 mid a little more forward.
The most surprising difference is the sound stage separation. The V20 seem to push the left and right further out away from the central image. But against the G6 it seems somehow false, a little phasey. Like some spacialiser or cross-feed effect. It is relatively subtle, but I wouldn't put it down to crosstalk, and isn't obvious on all tracks. Please note I have the V20 with B&O stamped on the back. Whether B&O have made any changes to the other V20s is still not clear.
Edit: I just recalled the track which showed this may be SACD downmixes to 2.0, so the original may be a 5.1, causing there to be more phase differences for the V20 to work on. Not sure.
Between these two the G6 has it by a hair. If you have the V20, getting the G6 may make you smile, but I wouldn't recommend it as a necessary upgrade. The V20 is really good already, and there is little between them