With respect to the statement "modern entry level > vintage top level", it makes some intuitive sense but all my bikes are still on SRAM 10 speed and I've never felt compelled to replace them with modern Claris or Sora. I've always built my frames up with lightly used parts because that's what I can afford, but I do get that there's a certain sense of satisfaction building a frame up with all new components. Before I converted to SRAM 10 speed I've ridden Shimano Tiagra and Ultegra. The only time I rode a Sora was on a rental about 14 years ago and it was just fine.