I have had Duramax trucks going back to 2002. I'm on my 2nd 2020 Duramax that is now pushing 90k. The Duramax is awesome. I get it, if you don't tow much it is overkill especially given the added cost. The reality is they drive great loaded or just daily driving, better than the gas in both scenarios IMO. They tow sooo nice, low RPM's, no revving and incredible power and now the 24 is even more capable...
Our work trucks are 6.6 gas trucks. I used one of them for a couple weeks while my DMax was having a def heater recall done. The gas truck got the job done but revved alot and after towing with it for the weekend (35' gooseneck trailer) it simply wears you out more on a long drive drive.
All of this said, I ordered my first gas truck in a long time due to the 10spd Allison. I'm hopeful the 10spd will reduce the huge downshifts and revs needed to keep the larger trailers moving. My new truck is currently "in-transit" and I'll admit I'm still not sure I made the right choice. It is saving me $9390.00 though. Time will tell, really looking forward to the real world difference and hoping it works out. Worst case I go back to diesel.