Well I for one will say, yes I check the mirrors often to be sure the 5er is still back there!
We moved from a 2001 Ram 2500 CTD to a 2016 Ram 3500 DRW HO Aisin, the difference was amazing. The 2001 had a 3.55 rear and the 2016 3.73, NV4500 to Aisin.
The 2001 with small chip still worked to get going, the 2016 not nearly at all, our 5er is a bit over 13K. Depending on road and traffic tow between 65 and 70, 5er is riding on LT tires so that isn't an issue.
I am amazed when traveling at 70 that I will get passed, by both other larger 5er's and TT!