It will never fully replace my Mac, but if you are working with ratios
At Home
iPP: 100%
Mac: 0%
At Work:
iPP: 70%
Mac: 30%
For me the 30% is still the critical 30% that makes me the most money for my time. But that is still a beautiful trade-off for me. I expected too much from an iPad it being a laptop replacement, but I found it works best by using the device that is in front of you, and more and more it is the iPad that is getting the job done.
On the other hand, I still like working on a 27-inch screen for 3-4 hour stretches.
What I find interesting is in conference calls, screen shares, and watching video, I use the iPP more than the MBP because it is faster, and 100% more silent, and then it makes my MBA experience better because I do not have to run these CPU heavy apps since I have delegated them onto the iPad.
My MBA has actually turned into a Chromebook, because all it opens is Chrome, all others apps I prefer using an iPad.