I traded my 05 6.0 after 7 years ~170k hard miles. Oil leak, EGR valve was the only repairs I had to do during the 7 years.
My BIL owned a 04 6.0 and I recall he replaced a EGR valve and a FICM during ~5 years of ownership and I know he ran the snot out of that truck. He traded that truck on a 09 RAM 6.7 cummins and had constant issues with CEL's, soot clogging EGR, turbo, soot clogged DPF and unloaded it after 9 months thinking he was getting a better truck.
Both of us considered those trucks overall reliability and durability to be outstanding.