OK so after a few miles driven, some in an ambient temp of 36 deg C the oil averages 10deg cooler for any given driving style apart from hard driving on the hottest days, it averages around 90deg around town.
Warm up is the same - very quick.
My theory is that the oil has a slightly easier life - the cooler oil will help keep engine temp down and reduce load on the fragile water pump.
I also noticed wear marks on the OEM item where it moves up and down, so all that metal has gone into the oil over time, the replacement is static.
Is it worth it? who know....