I have an NW-ZX507, also in part for the USB, but overall after using it for a while I've pretty much relegated it to a backup. I guess I was expecting it to be a step up from the ZX300, but the audio side is pretty much identical, the slightly bigger screen in practice is no better (and I had to add a matte Brotec AirGlass screen protector to cut down on reflections to match the ZX300 screen quality. I have the USB-C port, but unlike the ZX300, the ZX507 doesn't have a Mass Storage mode. I have a Mac, and as Sony dropped their media content management software I either have to use Android File Transfer (clunky, can't be automated), ActiveSync (very slow), or pull the SD card whenever I sync. With the ZX300 when I want to sync I use Carbon Copy Cloner, so when I plug in my ZX300 USB cable to the Mac it powers up, then automatically synchronises my music library, and ejects - and the ZX300 automatically updates the music library, but on the ZX507 it has to be done manually. Also the ZX507 battery is smaller, and even with all apps removed (apart from Music) it's quite power hungry - battery lasts about two thirds the life of the ZX300 and also nearly double the price of the ZX300. Plus, none of the additional features it has are anything I need. For me, it was a bad decision; should have waited and done more research.