I did!
Last year I got both in order to test drive them. I kept the regular 6.
The Plus was underpowered and too laggy for me. On top of that even the regular 6 felt like it needed some getting used to.
This year the 6S Plus feels right in my hands, thanks to the year spent with the 6.
Moreover, the new processor and 2 gigs of ram make this phone what the 6 Plus should've been!
Needless to say, I feel safer putting this phone in my pockets as supposed to last year's model when it felt really fragile and I was afraid of bending it.