Kukje uses a low temp continual regen. That works pretty well for most people in most circumstances, but it has been a problem for a few in cold climated whose machines don't get run hard. They added a mechanism to do operator commanded regens. It uses an exhaust valve in the tailpipe to keep heat in the DPF.
All this allows them to keep using the well proven mechanical injection with indirect injection and a clone of the Bosch VE pump. If it ever goes bad there should be plenty of people who can fix it.
With the models that can't do regens the only electronics are the data recorder which monitors the DPF. You can unplug the data recorder and it runs fine. With the update to regens, the instrument panel is also electronic and is a little more integrated with the data recorder. Now if you unplug the data recorder there's a light on the instrument panel that won't go out. I think it's a trouble light of some sort. Mine's an older no regen model, so I'm going off someone else's post and might be remembering it wrong.
If I had my choice I'd prefer the newer regen-capable model. My 3725 has been flawless for 320 hours but initially I was worried that I might have DPF problems. Evidently I was worrying about nothing, it's been fine.