I have some experience. I am very happy with mine, even coming from a diesel truck. I have some videos towing 11,500# and 14,000# 5ers with mine that will help you. The 14k unit is over 40' long and belongs to a friend. I towed it as a test. When compred to his 2014 Ram 3500 with the 6.7L Cummins, the 0-60 times were nearly identical at 22 seconds towing his huge RV. My 5er is 37' and weighs 11500# give or take, and the Hemi pulls it in 5th gear at about 2200 RPM and gets about 7-9mpg. I pulled the same RV with a 2007 5.9L Cummins and got 10-11mpg.
Link to videos