DEF in John Deere

[FarmRanger]

I heard a rumour that John Deere will be switching all their engines over to using DEF (Diesel exhaust fluid - urea). Now my dilema is whether to buy a new combine now and take a chance on it being a possible white elephant in a couple of years... Or wait and rattle along with the old clunker for a couple more years.
Thoughts?

[bsigg]

We bought a S680 and these new engines are so
smooth and use way less fuel.

I guess it comes down to whether you like the EGR
system or SCR system.

IMO the SCR will be more efficient, but am
wondering if the John Deere will use a hybrid of
both EGR and SCR so as to not require as much DEF.

All these acronyms are giving me a headache.