I just don't see the utility of having "notable" anywhere as a designation in the "list of choirs". Presumably, if this is Wikipedia and the essence of an item's existence on Wikipedia is its notability, then notability should be a precursor for inclusion of any choir in any part of the list.
Absolutely! I'm a little dubious as to the purpose of/need for the list in the first place (but I'll make that argument over on the page itself). The designation of "notable" in just some of the category headings is entirely unnecessary. BTW, I'm one of the founders of ChoralNet (where I maintain the world's largest directory of choir websites), and Chor Leoni is indeed extremely notable, without a doubt!