I made a test with the Fujinon XF 14mm f/2.8 - a phenomenal windangle-lens with very little optical DISTORTION. To test this I stiched 2 separate 14mm-exposures into 1 large panorama. As you see there is no misalignement or barrel-distortion to see - Look at the row of windows on the 2nd floor - straigth as an arrow ! Look at the diagonal of tables on the left. Very good lens. My favorite now! I just LOVE it!
Normally you would not tak a X-E1 with a 27mm pancake to a Rock Concert. But thats exactly what I did, because alle camera with exchangable lenses werer banned and had to be deposited at the entrance. I convinced the security-guard that my set was an "ordinary point-and-shoot compact" - and got away with it.
You would not take a X-E1 + 27mm f/2.8 pancake to å rock concert, would you? Weel, I am glad I did. Because when I arrived, I learned that ALL cameras with exchangeable lenses were BANNED inside the venue. I convinced the Security-Guard at the entrace that my X-E1 was just an ordinary compact camera - and it worked! :o) I was admittet!