A lot cheaper
Well yes,
the thought of US customs is something I'm thinking about. The options of TAM or TAP I have looked at, and they don't seem to be that much shorter in terms of total journey time. There is however a difference in price of around £350 in favour of the delta option. Having just written that I wonder if I have got it wrong. But its late and so I will start checking it again tomorrow. Thanks for the replies.
s