Yes I do own an air 11" 2010 model that has been used all of 2 times. My MBP 15" is much better for me when Im sat at a desk and my ipad works better when Im on the go. If I didnt won a MBP then maybe I would find it more useful but as it is I still see it as a glorified netbook. Yes the specs are much better than any netbook I have seen but it still doesnt compare to the MBP and it still isnt as usable on the go as my ipad.
By your logic then you should have a maxed Mac Pro/iMac for when you're at your desk "because it's better" and an iPad for on-the-go. You have to find the right machine for your own personal needs as I'm sure you know, and where does the OP specify he/she will need an ethernet port or a dedicated graphics card or expandability or a faster chip?
You haven't once specified what you actually use your MBP for (be it PS, Aperture or whatever) so the OP can't actually use your information at all to compare your experiences to his/her needs! For a lot of people the MBA will feel faster because of the SSD - it depends what your usage is.
It sounds to me like the OP is looking for one device not two. Therefore based on the information I would say he/she would be better off getting the MBA as a compromise between portability and power. After all you seem to be suggesting he/she buys a MBP and an iPad as opposed to a MBA - potentially costing twice as much.
I use a 13" 2011 MBA as my main machine and it's great. The SSD makes it really fast for a lot of tasks and hooked up to an external monitor I have more than enough power and screen space to browse the web, watch movies, play games, write code etc. It's great if you want to take it somewhere other than your desk too, much less of a burden to carry around than a MBP in my experience.