Thanks very much for the articles, Dennis. I have been wondering about this sort of thing but have not done the footwork to track down such old articles. It was quite informative.
I have a 'cord V and a 'flex (not sure of the model yet, but it's a '48 or '49), both with Xenar lenses. I was happy to see the Rome photo as well. It does a great job of showing what a Xenar lens is capable of producing.
In his purchasable article Harry Fleenor, the Rollei repairman, states that because the lenses were assembled by various technicians at the factory, there is variation from lens to lens. I got the impression that sometimes even Planars can be sub-optimal, and that certain Xenars can be exceptional. But he further notes that even "soft" lenses are such in comparison to other lenses in the family of Rollei offerings; compared with other lenses of the time, they are still all outstanding lenses.
I'm not a "gear freak" necessarily. I just want to use my Rolleis for some serious work to be enlarged, typically to 11x14, but perhaps 16x20. With a medium format negative and a crisp lens, I should be happy with the results I get from my gear.