Roughly two years ago, the KJ's PCV puck was replaced with a new OEM unit. Today, I noticed that it's puking oil all over the valve cover about as badly as the old one was. Is this about right for their longevity, or is something else going on?
There is a Provent 200 installed along with Sasquatch silicone hoses, but I doubt that has anything to do with it.

I would remove the CCV Puck, take it apart and inspect everything. Also inspect and clean out the "J" tube drain as pictured below and make sure it is not stopped up. If it stops up, oil would back up in the puck instead of draining out as it should. I believe there are some "O" ring type seals that can also be inspected or replaced.



View from inside valve cover underneath CCV Puck.

Keeping the "J tube" (loop seal) clear is very important. It is even mentioned in an obscure entry in the FSM. I believe a large number of CRD's are driving around with this clogged, hence exasperating oil carry over issues. It can be difficult to get a clogged one cleared initially, but once completed it is fairly easy to keep clean as in WWDiesel's photos. I pop mine off to clean every second oil change. Neither of my CRD's experience noticeable oil carry over now and I do not have Provents or equivalent separators installed.

I had nothing better to do, so I grabbed a pipe cleaner and went out to the Jeep.
This is what I learned:
1. The CCV outlet was not perfectly round. Like maybe it got hot and warped. Maybe that’s why oil was leaking.
2. The CCV puck gets brittle with age. Trying open it up could break it.
3. Finding the J tube is a poke of faith. Almost impossible to see.
4. Carb cleaner dissolves latex bandaids. I already knew that carb cleaner on an open wound was painful. Now I have pain AND a sticky mess all over my index finger.

Use Brake Cleaner and wear some mechanics gloves, much less painful.

Yes - it is a valve, that's why I said it has a rubber flap inside and a weak spring. That's ALL that is inside it. The idea is that the turbo suction draws out the air and any combustible gasses (what little might be there) from the block, and keeps the vacuum pump discharge from building up pressure. Then if the turbo suction gets too strong, the flap is sucked closed and prevents the block from (maybe) imploding or inhaling a gasket until the suction backs off and the spring opens the flap again.

Keeps the block between 1 psi and 1 inch of vaccum / -1 psi or so.

That's all it does.

That is not entirely correct. It is also a cyclonic separator. Hence the drain in the bottom of it that requires a "loop seal or J tube" functioning properly to drain the separated oil back into the cam cover. Section 9 - 1675 of the FSM refers to this as an "Separator-Oil" and instructs to keep the drain hole clean.

Did you put a hose clamp around the outlet hose?

I would remove the CCV Puck, take it apart and inspect everything. Also inspect and clean out the "J" tube drain as pictured below and make sure it is not stopped up. If it stops up, oil would back up in the puck instead of draining out as it should. I believe there are some "O" ring type seals that can also be inspected or replaced.

It is also a cyclonic separator. Hence the drain in the bottom of it that requires a "loop seal or J tube" functioning properly to drain the separated oil back into the cam cover. Section 9 - 1675 of the FSM refers to this as an "Separator-Oil" and instructs to keep the drain hole clean.

Interesting - it's basically doing what the Provent does, but internally rather than externally and using a different separation method. Hadn't caught on to that before.
In any event, if we can get some clear weather this weekend, I'll give it a cleaning and see what happens. It is also possible that it has worn out as well; even though it's only been in there a little over two years, that equates to around 53,000 miles. Despite the fact that we've put a decent number of miles on the CRD in a relatively short time, it's easy to overlook.