I was told by someone here to stay away from DD engine, didn't take much to realize I should stay away from MB engine at all cost. Fortunately, with CAT engine, you're not as blinded as getting into Mercedes engine. As stated, it's not the durability of the motor, but finding the part. CAT owner won't be faced with such difficulties finding right parts, some advertise genuine CAT C7 oil filter as low as $3.
I found some useful internet place, where people have interesting and active discussion on this particular engine. The moderator seem to be very resourceful, possibly working for CAT, but I can never tell. He mentioned that CAT's authorized service dealer is offering in-frame overhaul at $3000 or $6000 for complete overhaul, a steal if you don't want to grease your hands, but it won't apply to your need. If you're interested I'll post the link.