Ok, so I guess my choice is:
Panny G20 - 42" - £800
LG 590 - 50" - £700
I'm edging toward the Panny simply because I'm viewing it from around 8ft away, dare I say it, but I'm thinking a 50" would be too big. Ideally I'd not be looking for a replacement in the next 3-5 years, and in that time I expect to have a house (12mth/18mth) with an A/V room, in which case a 50" would be perfect.
I was waiting for 3D, but tbh I now couldn't care less. Until they develop 3D TV without glasses, or even better projectors I'll buy in. For now even Freeview HD would be a massive bonus.