Good to hear that!
I did change tyres for the winter and and I can confirm that the noise has gone.
Up to 130km/h we enjoy the ride in quietness.
Here in Belgium, i30 tourer have Continental summer tyres (at least mine had). They're more refined than Hankook but still Michelin or Goodyear might be more refined.
For the winter Continental WinterTyres are really awesome and I can recommend.
Seat Leon is kinda of inferior vw golf brother and I would never exchange it for the i30. You feel inside it's a category B product. Same applies for Skoda.
I drove golf 7 & audi a3 sportback for 1 year and I don't really miss them (maybe a3 a little bit
). Don't say they're worse but during test drive with Skoda, we simply said no after 20 minutes.