If you're just going to delete then there is no difference between a pre or post DEF for all intents. That said there is nothing to not like about a DEF equipped truck.
Life expectancy on the 6.7 is a B50 of 400,000. What takes these engines down is contaminants in the fluids or a turbo issue. Both of those are easy to deal with really. Keep up on filters/lubricants and exercise the turbo occasionally. Unlike a gasser a turbo diesel really needs to be worked periodically to heat everything up and blow it out.
Life expectancy on the 6.7 is a B50 of 400,000. What takes these engines down is contaminants in the fluids or a turbo issue. Both of those are easy to deal with really. Keep up on filters/lubricants and exercise the turbo occasionally. Unlike a gasser a turbo diesel really needs to be worked periodically to heat everything up and blow it out.