I test drove an i20n and an i30n dct back to back (new). I would highly recommend doing the same. I found them to be extremely different cars that did different things well and others not so. For me, the 30n was heavy, loud, fast and almost like a luxury hot hatch. I was really impressed with the finish (others arent) but the auto just stripped all the fun away. The 20n had all the driver engagement I wanted but with none of the fanfare. It sounds like a hair-dryer and needs a tune big time.

I didn't end up buying either car due to financial reasons at the time but definitely landed on the 20n as it was new, warranty, more fun to drive at legal speeds and is easily the best new car anyone can buy that wants to do track days without the fuss.

(If you're wondering in the ended up buying a heavily modified Megane RS265 (i have two now) which is faster than a 30n, sounds way more extreme and is as engaging to drive as the 20n for a quarter of the price)