The German guitar group called Gitec, who focus on physics and other scientific principles of electric guitars, as just posted another scientific article on AlNiCo magnetshttps://gitec-forum.de/wp/wp-content/uploads/2017/12/Z35E_Alnico-Magnets.pdf The focus of this article is mostly about how the degaussing of AlNiCo pole pieces (as opposed to bar under mount magnets) effects the electrical properties of a pickup. Their finding is that when AlNiCo pole pieces lose magnetism, the inductance of the pickup drops slightly, as well as increasing the resonant peak slightly. AlNiCo 5 doesn't this more prominently than AlNiCo 2. Degaussed AlNiCo 5 also shows a slightly higher Q factor as well, whereas degaussed AlNiCo 2 causes it to change very little. These differences are probably too small to be heard, but it's interesting to know that they occur. If the differences could be heard, it would mean that weakened AlNiCo would produce a brighter sound, more so with AlNiCo 5 than AlNiCo 2. Given that the difference is small, you might be wondering "so what?", well with all the unsourced claims that are made about what magnets can and can't do for a guitar pickup, there's almost as much value in knowing what doesn't happen as there is what does. It's also worth noting that decreasing gauss strength of pole pieces changes how the pickup pulls against the strings, and that makes for a difference, though it is a physical difference as opposed to an electrical one, and is approximately the same as raising or lowering pickups. Gitec has been posting research for years in the German language. They have recently been translating a lot of their work into English https://gitec-forum.de/wp/en/ , so if you like science and you like guitars, check out their other work as well.