had a 08 super cab after a trip that the wife sat in the back we bought a crew cab. She is not a big person 5'4 105lbs, but the seat back being that vertical and seemed to be lacking on padding was what bothered her, also the seat surface is shorter, not doubt the 150 extra cab has better seating.
With that said if you never plan to ever never have anyone back there then buy a super cab, you will save $$$ and payload.
2016 Ford F350 crew cab dually 6.7 platinum with heavy tow and 4:30 gears
2015 Carbon 327 with a BMW k1600 and Canam 1k inside