Love my 6.7. Pulls my 40' toyhauler like nothing. Just set the cruise at 70, click haul mode. Just rattles down the road w/o a care.
Nothing wrong with the 68RFE if stock power levels are retained and you watch your trans temps on climbs. I have one with 210k on it that has towed an 18k pound 5th wheel most of its life. Its all original and still going strong. Can't ask for much more than that for an automatic. Also the Aisin has much more frequent service intervals (30k vs 50k) than the 68RFE so there will be increased maintenance costs if you go that route.
The single greatest thing i did to my Ram 2500 is have the trans tuned. I usually run around on the 60hp tune for the engine, but the trans tuning i what made the truck more enjoyable to drive. Once in a while ill switch to the 200hp tune to annoy my wife and the trans does just fine. I dont boost launch or anything though. I wanna upgrade the valvebody, and up the pressure some more. Another key to long 68RFE life, is to NOT put giant wheels and tires on the truck..
If the market doesn't get back on track any time soon, so long to my choice of Godzilla Super Duty and hello custom '78 Bronco with a Godzilla and Tremec Magnum 6spd. It would probably be the same wait and/or money either way. One of them, however, would be completely free of computer BS - well worth the price of admission, imo.