I've seen these two sets side-by-side on a couple of occasions now, and I thought the V20 shaded it in terms of pic quality: better colour balance, deeper blacks, less reflective screen. That said, motion looked slightly better on the G30, which of course was one of the gripes V20 owners reported. Overall, however, there's very little in it.
I won't bleat on about buzzing from the V20, though I really couldn't tell if the G30 was any better in this respect, as the shop was noisy, with flourescent lights that hummed louder than any of the TVs.
Also bear in mind that the G30 doesn't have an integrated Freesat tuner, which may or may not concern you.