From what I gather on the FORD version of this motor the biggest issues were the EGR system, fuel filter, water seperators, and the biggie was the DPF/REGEN system.
That motor NEEDS CLEAN FUEL..no water, no contaminants. That the same issue for most all diesels BUT the injection systems on the 6.4's were very expensice to fix if the need aros.
The DPF/REGEN process that is used for the FORD version was the thing most owenrs found to be troublesome. Basically during the REGEN process extra fuel is injected to heat up the Diesel Particulte Filter in teh exhaust. For a couple different reasons this could lead to fuel getting into the oil, thus "creating" more oil/fluid in the oil pan.
If those isues arent present in the MAXXFORCE version, then from what I understand, its a reasonably stout motor.
My father owns a 2010 ford Truck with this motor and he is religous about the fuel filter, water seperator, and keeping en eye on oil levels. He plans on eliminating the DPF and tuning out the regen process.