In my humble opinion, the 68RFE is the way to go in the SRW. First, there's been a bump in torque to 850 lb ft. Next, they are back to the 3.73 gears. The max trailer weight rating is now over 20k with that config, and you don't have the maintenance schedule of the AISIN. With the AISIN, you'd get a max trailer weight rating of a hair over 25k, but you wouldn't catch me towing a trailer that heavy with an SRW - that's dually territory. I don't even understand how you'd achieve such thing, quite frankly, because it seems to me the tongue weight of such a heavy trailer would be overloading the tires. Lastly, as has been talked about quite a bit - you're only getting the max torque of the HO when the conditions are perfect to where the computer "allows" you to have it, which is when the stars align. Just my two cents.
You achieve it by having a suitable sized goose neck and understanding how to load it. I agree that having a dually at that weight would be ideal, but I'm not towing that much all the time. I agree, though, on the Aisin. If you are looking for sporty performance, this is not the transmission for you.