The 6.7 and 68rfe is a MUCH better combo, only way I'd go back to a 5.9 is a fully mechanical 12 valve. Nothing wrong with CR 5.9's....but for those who think the 6.7 is issue prone...doesn't have "current" personal experience with them. I've owned a 12 valve, 24 valve and a CR.....the 6.7 is a beast compared none of my other trucks were stock.
Nothing against DEF either...and will have a truck with it someday I'm sure...but if you can avoid/delete it, one less thing to buy and maintain. Although I do agree, EGR's suck...which is why mine fell off.