Is it really that different on the north side?
no, not that different, they’re 40 miles apart but the geology is similar.
if you’re happy with your tyres then stick with them, people are giving you advice based on local experience, there’s no rule that says you have to follow it.
For most people, most of the year, something like a Mud-X or Conti Baron is fine on the Downs. They’re not ‘slow’ on hardpack but will get you up and down stuff when it gets wet and/or muddy. There’s lots of people who put a purgatory or something on the front year round and have a less knobbly tyre at the back.