Bold claim to make when you don't know the starting specs nor upgrade prices. Remember the $999 MBA is only 8GB RAM & 256GB SSD. It's not exactly a good configuration, and Apple's upgrade pricing means it quickly becomes a $1400-$1600 MBA when you give it modern specs on those two aspects.

The X1 Titanium Yoga then offers a touch screen, a better aspect ratio, convertible usage, and significantly faster multi-core performance, at least in bursts. That can easily be worth another $400 depending on the use case & personal preferences. It's also fully possible the X1 Titanium Yoga will be overpriced, of course.