No comparison. Even the base model Wacom pad beats the Intuos / iPad combination. The Wacom pad wins every time.
If you're looking for extreme portability / on the fly use; then yes, the intuos pen is your friend. Otherwise, you may be better off with an MBA 11" and a small Wacom pad.
Actually portability is handy but if I use the actual machine on the site, clients will attempt to make changes there so I've learned its best to do the real work in the studio or home office and use the tablet as a preview device for clients to see if meeting in person. That prevents them from manipulating the creative into making changes on the spot without the alteration fees they like to get away with.
Something to think about. However I love the Cintiq portable device and think its handy for "on the go" conceptual work and flesh it out at the studio. I mean would you be doing secret projects on an NDA at a coffeeshop with the tablet? But MBA with a standard tablet hooked to it is an idea and even though I've an iMac already. My PowerBook g4 titanium is way outdated for this work now :/.
But if I take my Wacom tablet for the MBA then that's not a bad idea. I would have to copy and install apps on it and both machines would have the same files.
One reason I use Dropbox with my 1g iPad to store my conceptual art via sketchbook pro or procreate.