I assume deleting the emissions stuff significantly improves the reliability.
100%.These engines had a awful DPF/EGR design. In regen (burning off soot trapped in the DPF) the system would inject fuel into the rear two cylinders during the exhaust stroke raising the exhaust temperature to point where the soot is burned off. Trouble was, that excessive heat caused all kinds of problems; cracked pistons (in the regen cylinders) failed EGR coolers, failed oil coolers, coolant cavitation, cracked heads, cracked turbo up-pipes, not to mention the horrific fuel economy that these would get during an active regen (think 6-8 mpg)....it was a trainwreck. My truck only has 80,000 km on a drop in Ford engine so it was worth deleting to allow it to live a decent life.
This engine was known as the 150,000 mile throwaway. If left with its systems the engine would rarely live longer than that. Deleted, many have double that mileage and more.