I'm also a NS-10m user for years back then. But I ditched it for HS-80m as I need more extented frequency response due to the work I'm doing. I'm not very sure about HS-50m, though, but I love my HS-80m. HS80m and HS-50m curve is "slightly" not the same, but curves alone cannot determine the final product. IMO from using my HS-80m, it sounded pretty much like NS-10m (provided you switch on the 2KHz boost at the back) with extended frequency response. (which is the reason why I picked it over others when I ditched my NS-10m.) I still like that NS-10m sound, and my HS-80m do have the fundamental of it. But of course, nothing sounds 100% the same in this world. NS-10m is a closed enclosure design, therefore, it will sound smoother than the HS-series. Whereas, HS-series is a bass-reflex/open-ported design, therefore, you will hear pple saying that it sounds harsher than NS-10m. There are pple who critics that it does not sounds like NS-10m at all. But IMO of using NS-10m for years, I would say if you are really familar with the sound, you will love it. But once again. at the end of the day, it's always the best for you to judge with your own ear coz you are the one who is using it, not these pple. Good luck!