I would include built-in 3G/4G LTE in portability too (no need for a second hotspot device). It's available on the iPad Air, not on the Surface Pro 2.
From his article regarding price (because Baytrail is cheaper compared to i5):
The iPad Air starts at $499, the Surface Pro 2, at $899. No contest here if price is the deciding factor and you don't need a hybrid.
From his article regarding weight(because baytrail-tablets are fanless and lighter):
No contest here. The iPad Air is a one-pound wonder. The Surface Pro 2 doubles that to two pounds.
Regarding Memory (you need 64-bit-Baytrail-Atom-Z3795 in order to adress 4GB of RAM)
All that extra memory in the Pro 2 (4GB standard) makes a difference too. Multitasking is fast and fluid. Not so on the iPad.
Two things I have added: - 128GB eMMC (because this would be my top of the heap-config and this is totally do-able) - Wacom Stylus (because a Wacom-Stylus is a premium stylus-experience - I enjoy working with the Wacom Stylus on a Samsung ATIV 500-Win8-Tablet)