Newer motors?

I have a friend that wants to purchase a new/newer truck. I am an old school guy all my tractors are older trucks ranging from 1985-2005. I have had a great deal of success with all of them. All are caterpillar 3406b, 3406e, or c-15. How do the new cummins motors stack up against the older cat motors? I have no experience with the def system they seem like a waste of money to me. But he will be buying a new w-9 with a cummins. Will they go the distance or do they not even come close to the durability of the older cats? I know everyone's opinion is different but if anyone has owned both style motors if you could just tell me your experience I would appreciate it.
thanks,

 

Egr sensor issues has come up a lot when I talk to techs. They said b/c they put the sensor to close to the turbo and the sensor takes to much heat which causes it to go prematurely. Thank you for your input. I will pass this information on. What about def system? Any problems and how much more out of your pocket to run? My advise to him was to maybe look into a glider kit. But only b/c my knowledge only extends to the c-15 cat. I have no experience to share with him on any motor newer then 2005.

 

Jason6541 have they said anything to you on why your eaten up cam bearings? That is not a lot of miles to have those types of issues. Normal wear is more in the 700k range, yeah?

 

Yeah that's my opinion as well, but if he goes new the only way not to have that is glider kit. I just don't think a new one is worth the 149,000$ they want for it.