TBH vegalo upgrading from 42 to 50 inch will not make that much difference, if you really want to upgrade then go for the 60 inch for sure. BTW where will you be watching this TV? I hope your front room is HUGE.
Can I just ask if you love your current TV then why change? and TBH I would also change for the bigger one, but I think that its just a man thing, second thoughts instead of changing the TV just get yourself a new recliner or something like that.
Well with an answer like that I bet your mind is already made up, a 50 inch screen it is then, enjoy watching it and see you in the opticians shortly, LOL.