DEF may "work", but the darned things are VERY complicated and fairly unreliable. The company I work for keeps 3 Cummins Techs working at one of our locations 5 days a week full time doing warranty work. That is at one location and we have 222 Service centers, and operate over 6400 trucks. The science behind the technology may be sound, but the implementation leaves something to be desired.
I can say that the systems are "cussed" daily and thoroughly, without fail.
Oh, the International system was invented and deployed by Caterpillar. When they couldn't make it work, they sold the C-13 and C-15 engine and emissions manufacturing rights to International and went out of the onroad diesel engine business.
Ron.