no it's not the same guy ..is that why you dug up a 6 month old thread?
Just for the record I think the Steve guy above has got it wrong completely in terms of which hoses is for what. But he's right in saying you are (were) worrying about nothing. The cooling system is pressurized and will only allow so much water IN as much as has come out through the thermostat. The radiator no matter how good will never make the water freezing cold, only a bit colder than what it was when it came out of the engine.
Other important points which were probably mentioned already .. the thermostat is not an on/off switch, it opens slowly from 82c to 95c on the NEO. Bigger radiator that cools the coolant much better will just result in the thermostat opening and closing more often, nothing else.