Well misplant I agree to most of what you mention however there is a basic ID key to atleast narrow the cactus to a few possible candidates. Different growing conditions; pot vs land, full sun vs shade, and possibly feeding conditions or some other factors will play into characteristics as well as genetics. I guess I could be wrong considering some Peruvianus localities look on par with cuzco. You do have lots of experience and quite the collection and I am only starting really so
Also some of your bridgesii (hybrids) planted in the ground have impressive diameters and I would likely misID some as Pachanoi/Peruvianus.
I don't claim to be a pro ID'er and also prefer to just group plants rather than try to find an 'exact' ID. BTW I'd call those all pachanoi/peruvianus as far as I can tell from afar. The Yellow tag is the more common pachanoi available here in the states and the others probably more accepted as peruvianus. How much time elapsed between the two photos? 2 years or less?
plantlight I think this issue comes up once in a while do to the way people label or talk about certain plants like T.Huarazensis. It is a Pachanoi from around Huara but rather than labeling it T. Pachanoi var(locality?) Huarazensis they did similar to you. Same goes with a few other plants from my understanding like T. puquiensis,
T. ayacucho, and T. puquio. Some consider them pachanoi others peruvianus I just call them pachanoi as I see them as the same.
You should consider just collecting cuttings from 'trusted' sources like misplant and other established members in the community. Buying from eBay or other questionable sources may lead to issues in the future like MANY people have grown peruvianus from a source (BBB?)and it was cuzco and inactive. Some people just keep what the seller had and kept record of the seller so like Peruvianus (WSS) or w.e.
I personally like the way cuzco look and tend to use it as a grafting stock... If I had the space and land I would have a few growing as they are quite impressive and robust growers.