Well, I've had enough. Called Peter Tyson this morning and arranged the return. I should add, I've no issue whatsoever with Peter Tyson, who have been perfectly reasonable throughout.
I could have just about coped with the floating blacks and motion issues, but the buzz from the TV has increased in volume since I first turned it on. Now, even with the volume just below half (i.e. loud enough to annoy the neighbours), I still hear a high pitched whine from the TV. The G10 made a bit of noise, but buzzing from the V20, in my opinion, is far worse and seems to have increased in the short space of time I've owned it.
Not sure what my next move should be. Maybe a call to Richer Sounds about rising blacks on my G10 is in order. Since the G10 was purchased with a five year warranty, perhaps they'll be sympathetic. However, as Panasonic refuse to acknowledge this is a problem and have a class action law suit pending regarding MLL, I'm not sure how I'll get on.
I'm now looking forward to reconnecting the G10. Sure, the picture will look washed out, particularly during dark scenes, but at least I'll have no flicker or shifts in contrast, and that 100Hz motion will be a dream to watch compared with the V20.
I think I've had my fill of Panasonic televisions. In fact, all considered, I may buy a Humax Freesat PVR and defect to a local dimming LED TV...