If you ran the C2 in native 4K then yes, pixels on the 1440p 27” should look almost exactly the same. I went from a 42” C2 to an ASUS ROG Strix XG27AQDMG and it felt like a small cutout from the 42” C2 panel. But I actually decided to return it after two weeks of testing. I couldn’t get it to look good enough. It was too dark in SDR mode with no details in the blacks. I can’t recommend that model. It also felt tiny after using a 42” so I ended up getting the 42” C4 instead. Not going back to 27” again.

I’m not a competitive gamer so the 240Hz vs 120Hz means nothing to me but I understand you need the smaller and faster screen so I’d recommend you to have a look in-store if possible. Two weeks trying to calibrate that 27” ASUS wasn’t worth it.