I concur with Michel; it's probably because of lens profile correction. Not sure how ACDSee does it; it may just take the image as it is without any correction.
You could try a trial of Elements 13 to see if anything changes.
The versions of Camera Raw that come with Photoshop have manual adjustments under the Lens Correction tab if you don't exactly like what you see by default.
The Sony RX100M3 has built-in lens corrections, which photoshop elements 11 should use.
Have you tried to open the dng file into the pse 11 editor to see how it looks in camera raw?
I opened the original jpeg and the converted ARW file in PSE11 and they looked the same, i.e. not distorted.
So I guess I will convert the ARW files and continue using PSE11.