I have only ridden a few 200k brevets, so do not count me as having any knowledge on riding PBP or any 1200k.
But, I do bike tours on a Rohloff bike. I also have two derailleur bikes that I use for bike touring. Thus I am one of those odd people that have knowledge and experience with both types of drivetrains. And I continue to use both types of drivetrains, not picking one over the other.
I would prefer a derailleur system for brevets. If I was starting from scratch today on setting up a rando bike for PBP it would probably be a 3X10 system, cables (not electronic shifting). But I am saying that in part because most of my bikes have triple cranks and I am used to them. I would investigate the latest wide range 1X systems before I firmed up the choice of 1 or 3 chainrings, as there are advantages to a 1X system with a single sequential shifter.
One thing that I think is fairly common with poor shifting on derailleur bikes is a bent hanger or a bent rear derailleur. That is something that won't happen to a Rohloff bike, but potential for that is also something that can be minimized with a derailleur bike with proper care when packing for transport, etc. Potential for a bent hanger or derailleur is not something that would drive my decision on which drivetrain to use. As noted by someone above, if your bike uses replaceable hangers, you can carry one, I carry one on bike tours on my bike that uses a replaceable hanger.
I understand the interest in a Rohloff. On a bike tour I like having a drive train that has all the small intricate parts in the hub, unlikely to be damaged in a crash or fall, I have confidence that the hub will keep working in adverse conditions. When touring, the thing I like the most about riding a bike with a Rohloff is the single sequential shifter, I do not have to think about cross chaining, do not have to think about which shifter to use next time I shift, ability to shift when stopped, etc.
Someone on this forum a few years ago bought a new Rohloff equipped bike and planned to use it for brevets. I found it interesting that a couple years later he bought a new titanium derailleur bike to use for brevets. I do not think he ever explained why he went from one drivetrain to the other. He planned to buy the Rohloff bike for touring and was thinking of also using the same bike for brevets, perhaps he found that the Rohloff bike that was built up to be a heavy duty touring machine was not the ideal rando bike? I did some searches and found some of his posts on his bikes.
https://www.bikeforums.net/long-dist...evet-bike.html
https://www.bikeforums.net/long-dist...onneuse-2.html
If you have any detailed questions, please let me know. I already went into more detail than I planned in this post, but I could elaborate on any specific aspects. I built up most of my bikes from parts. But I am ignorant on the latest newest derailleur systems.