Real nice article. Thank you for sharing. Your comparison of the 520 to the S4 I feel hits the nail on the head why WP users and potential WP users need to not get fixated on thinking "flagship" windows phones have to have all this high end specs that make the phones cost $650 plus and up. WP8/8.1 does not need it.
I feel like Android has truly destroyed the way the word "flagship" is perceived. In another topic, someone used the example that: instead of Samsung fixing the problems with TouchWiz, they just packed in stronger hardware... and that truly is an ***-backwards approach. Lag in high-end phones is almost always an issue with crappy coding.
Being a flagship phone isn't about throwing in the best-in-class processing and graphical unit, it's about creating a device that represents the underlying operating system the best. Which is why the Lumia 830 with it's meager SD400 can be considered a flagship. The definition has simply become lost and is seen through jaded eyes. If there is heavy emphasis on a function such as storage sense and the phone is unable to take advantage of that, having a SD800 won't make it the one to best represent the OS... which is why we have so many 1520 fans that weren't thrilled by the Lumia Icon. You don't need a Snapdragon 805 and the biggest and baddest Adreno if there is core optimization, and
big numbers don't *make* a flagship, they just impress people who aren't tech savvy.