Just to put things in perspective, I do own a Retina MBP 15, a MBA 11, an iPad Air and a Surface Pro 2. I've bought a Surface Pro 2 mainly because of the Wacom pen support. During the new managers seminars, I've found it valuable for note taking, etc. I can use Excel for finance spreadsheets or Microsoft Project on the Surface Pro although I could do the same on the MacBook Air.
From my experience, Surface Pro is a handicaped notebook with limited laptop capabilities. Their Type Cover, which works both as a keyboard and cover, works only on a flat surface. Battery life is much lower than advertised. I've done pretty much all kinds of optimizations to save battery, as an IT manager. On average, I can barely get more than five hours of work on "normal" settings. Any MacBook Air would do much better. Even the retina MacBook Pro, which has a much better screen and functionality would blow away the Surface.
So, Surface Pro 3 has just been released? As I said, and I'll repeat, the only reason to buy a Surface Pro is because of pen support. In any other aspects, a MacBook Air blows away any Surface Pro in terms of quality, battery life, name, reliability... And now, MS dropped Wacom support for some reasons: N-Trig is cheaper to licence and its hardware is incorporated into the pen (the screen is not active sensitive like on the Surface Pro 2). In that case, you'll be better served having your iPad Air and some active stylus. It's the same as the N-Trig and you keep the much slender iPad.
IPad has Pages, which is more advanced than Word, as far as my experience goes. And, it's free. And, with active stylus options on the iPad, it can beat a Surface Pro out the water. And, assuming you need to work with MS Project files, what about Bootcamp on that nice MacBook Air?
On June 6 the Microsoft store in my area will have the surface pro 3 demo unit, I will go to play with it,