A few points that I don't think saw, i.e. "everything I ever learned about modern derailer chains":
As long as the chain model number hasn't changed since the Shimano quick-link became available, sure the former 11s pin can understatedly be used on that Shimano 11s chain.
Quick links seem to be interchangeable between brands with 9s and 11s chain, but not so with 8 and 10s chains. SRAM 8s and 10s PowerLink connectors for example will not pivot freely on 8s and 10s Shimano chain, and may be difficult to install or remove.
The Shimano pins get better as one accumulates some experience with them.
Shimano pins without a snap-off, tapered extension must be installed with
extreme care and/or with more production-oriented tools, since the squared leading end of the pin tends strongly to eat a crescent-shaped piece out of the mating hole in the far-side outer link plate (with resultant loose fit where the "barb" feature is supposed to hold the pin in place).
All of Shimano's parts "instructions" have long since been reduced essentially to CYA verbage. Real instructions must be sourced online (such as the details about asymmetrical installation and having the connecting pin positioned only in the leading hole in the outer link).
I'll add that I've measured the dimensions of various chains, and found that Shimano chain tends to have more aggressive tooth-grabbing dimensions which makes a critical difference in 10s installations. Their 9s chains are also measurably wider inside of the outer plates vs. pin width, which quite noticeably affects front shifting performance in some installations.
Lastly, ordinary pliers can effect the needed "diagonal" decoupling force needed to easily remove even the quick links that snap forcefully in place, but the chain first needs to be bent like the letter "C" for the pliers to positioned on the link as needed. The jaw's teeth catch the diagonally-opposed edges of the outer link to force the sliding motion.
And I've never had or seen a problem with the re-use of a quick link on a chain having the same mileage as the quick link itself.
Editing here, to add that a Shimano chain link with a special pin can be removed by grinding away at the heads of the two pins, taking out half of the outer plate thickness as well. The link then slides out and a quick link can replace it. The grinding is a bit tedious with a Dremel unless the 1" diameter green stone is used (part number 85422 and available online if you Google it or search on Amazon). I've removed good chains from broken frames and made shorter work of the link removal at the bench grinder.
