@DYP , the KM engines started becoming really solid when the C1070 series came out. They fixed the registration and color consistency issues of earlier engines with this iteration. They addressed the registration by adding a 'swing' roller which moves each sheet to the exact same position before it enters the imaging unit. The color consistency was now managed in 2 places: 1. In the engine by printing swatches on the transfer belt between every print which are then read by internal densitometers (just about every brand has this). 2. In the relay unit that comes after the engine, there are spectrophotometers which read color patches on your media at your chosen intervals (every 100 sheets for example). Another big improvement was the decurling and anti-static features.
Using the same basic technology, they made additional upgrades and improvements with the C2070 series such as increased gsm handling, faster envelope printing speeds, and the availability of printing long sheets.
Then the C3070 series, saw a huge jump with the availability of the
IQ-501. You can read more on the KM website, but it has high speed cameras to read marks on the top and bottom of every single sheet to monitor registration, and spectrophotometers to measure color patches...but now on every single sheet instead of at intervals like the earlier generations.
All of this to say that the C83HC is built on the same engine as the C3070 - so yes, you can expect it to be very reliable for color consistency and registration.
FYI, I used to sell KM production gear. I can attest that the C10, 20, and 30xx series were very reliable for my clients when I was working there. I will say that having a good local service team who regularly does the PM's is a big part of that in my area. I now work at a shop with all KM gear, and I've been very happy with the reliability of the gear. Keep in mind the volume that the C3070/C83HC is designed for so you have the right expectations. I would only recommend that engine for up to ~50,000 impressions per month. Beyond that, I'd look into the C6085/C6100 series.