I tow a 9300 lb 5th wheel with a 2018 Ram 2500 6.4, 4.10 gears.
I tow in Oregon and the PNW and occasionally in NorCal.
On the freeway it will cruise easily at 60-65 mph or more if conditions are doable. In the mountains I lock out 6th and sometimes 5th depending on traffic and grades. I see 4500+ in the steeper grades. No biggie for me as it's only there for very short periods of time.
I don't have an issue with the 1-2 shifts. Yes it feels like a drop off on acceleration, but how often is that? I take off and hit the road for hours with out stopping. So maybe 3-4 times a day on a trip.
MPG's are low. 8.5-9 mpg. I would add that when not towing the trans is smooth as silk and the 1-2 shift is not noticeable at all. Only when trying to accelerate fast while towing do I notice it. 4.10's help IMO.
I came from a 12 Ram 2500 CTD and like the 6.4 better overall. I'm retired and do lots of short hops. In the winter the CTD was terrible at warm ups. I was it's worst enemy as far as emissions goes. The CTD definitely out tows the Hemi but thats just part of the overall experience. The Hemi is a lot easier to live with on a daily non towing scenario. If I towed heavier and more often then I'd 100% opt for the CTD.