Johnny,
Everything said above is good advice.
I pull a 9800lb RV trailer and love my Aisin, the only medium duty tranny on the market of HD pickups. I don't experience any "quirks" or "slam" shifts. It's just starting to break in at 6500 miles, and I'm getting 18mpg empty and 12.5 towing. There's no way a 68RFE will "double" that. My brother has a 2016 Aisin, and he gets 18.20mpg, sometimes 22. I don't expect that from my Aisin as the 2020 has more horsepower and a larger turbo. For me MPG is a mute subject as I bought it for its power.
Not wanting to start an argument, just want to give my Aisin experience - it's all good, and it performs as advertised, daily driving or towing.
Buy what you want, or you'll be sorry later. Like you, I probably don't need an Aisin, but I went for it because it's the strongest tranny of them all, plus I wanted an HO.