Yes I am......
I do a lot of 3D design work, photoshop, aperture, illustrator and web design, with a lot of multi-tasking.
My 11" air only likes the above software for very minor work. I did some full tests on it, and really cannot see how the 13" would be. able to perform as I would like [after looking at all the benchmarks]
Also the screen size is a very big deal, as the upgraded screen size on the 15" basically replaces the need for an external monitor. With the air I would spend my life plugging and un-plugging it ! Reduces a lot of clutter.
It all depends on what you use the computer for, as the MBA is my all time favourite mac! For most it is perfect, but not me.
In the end, just stick an SSD into the Macbookpro and watch it fly way beyond the air.
However, I will be back to the air probably when the Ivy Bridge chips are in it, and in the mean time will make the most of the power of the MBP.