I don't really care for the Core M version. Give me a Retina normal i7 and I will be perfectly happy. The most recent core M laptops haven't been great and I would prefer a fan in my laptop, especially if it is going to be so thin. I used my 2012 MBA for gaming (Dota 2, Hearthstone, Counter Strike GO) and it ran fine on medium-low settings but the fan kicked in and was going at max rpm. I don't think that the Core M could handle this, let alone keep the machine cool enough for this...
If you were wondering, my 11" Air is amazing 🙂 Love it to bits! It's not as small as you think it should be and the 16:9 aspect ratio helps loads. I have both a 13" Pro, 13" MacBook and 11" Air and whilst the others aren't shabby, I don't see a significant downgrade when I go to the Air. In the beginning, I thought i would feel a bit claustrophobic but its actually a great screen size, especially for portability.