You are correct - the Massey with SCR requires DEF - I looked over their brochure way too fast last night before my post.I do not agree to your statement on the DOC.
I'm running a long haul truck, with a EPA 2004 CAT c13 Acert engine. A DOC was part of Caterpillar's solution to comply with the EPA standards at that time.
The DOC held up to over 40.000 hours until it was finally plugged.
Long haul trucks do not always have a lots of load on the engine or run high Rpms.
To one of the previous posters, if it says SCR, it requires DEF.
I would go with any DOC model any time.